Horizontal velocity spirals with a clockwise rotation(downward looking) rate of 1.7?m^(-1), on average, were observed in the western and northern Yellow Sea from December 2006 to February 2007. With the observed therm...Horizontal velocity spirals with a clockwise rotation(downward looking) rate of 1.7?m^(-1), on average, were observed in the western and northern Yellow Sea from December 2006 to February 2007. With the observed thermal wind relation,the beta-spiral theory was used to explain the dynamics of spirals. It was found that the horizontal diffusion of geostrophic vortex stretching is likely to be a major mechanism for generating geostrophic spirals. Vertical advection associated with surface/bottom Ekman pumping and topography-induced upwelling is too weak to support these spirals. Strong wind stirring and large heat loss in wintertime lead to weak stratification and diminish the effects of vertical advection. The cooling effect and vertical diffusion are offset by an overwhelming contribution of horizontal diffusion in connection with vortex stretching. The Richardson number-dependent vertical eddy diffusivity reaches a magnitude of 10^(-4) m^2 s^(-1) on average. An eddy diffusivity of 2870 m^2 s^(-1) is required for dynamic balance by estimating the residual term. This obtained value of 10-4 m^2 s^(-1) is in good agreement with the estimation in terms of observed eddy activities. The suppressed and unsuppressed diffusivities in the observation region are 2752 and 2881 m^2 s^(-1), respectively, which supports a closed budget for velocity rotation.展开更多
The spiral has been studied for the first time in the book “About the spirals”, by Archimedes （Greece, 287-212 BC）. In America, the design of spirals seems to have been used previous to Archimedes＇ time, although...The spiral has been studied for the first time in the book “About the spirals”, by Archimedes （Greece, 287-212 BC）. In America, the design of spirals seems to have been used previous to Archimedes＇ time, although in the Northwest of Argentina the appearance of this figure in ceramics can be dated between the years 800 and 1,400 （AD）. The spiral is found in cave paintings, in pumpkin carvings and in pottery, particularly those painted inside of plates （pucos in Quechua language）.There can be seen simple linear spirals, double spirals and spirals filled with squares, spirals in two, facing each other symmetrically, as well as spirals joined to bodies of animals. The number of spires detected in the largest spiral is 12, a number of evidently sacred characteristics. When there are several spirals in an earthenware vessel, it can be seen that all of them spin to the same side whether it is clockwise or not. This could have been caused by the predominance of the use of either one hand or the other by the ancient artist. This paper is produced with computer methods used to design spirals in the computer, either Archimedes or the logarithmic ones. Finally, the book： “Man and his symbols” of the psychiatrist Carl Gustav Jung （1875-1961） help to understand this congruencies. In this paper, Mathematics is complemented with the Archeology of art and Psychology.展开更多
The source from MOC (Ministry of Commerce) releases that China’s outbound investment hit $6,920 million in 2005, rising by 53.6% while there were 1,067 new Chinese overseas operations as approved by MOC in 2005, 28.7...The source from MOC (Ministry of Commerce) releases that China’s outbound investment hit $6,920 million in 2005, rising by 53.6% while there were 1,067 new Chinese overseas operations as approved by MOC in 2005, 28.7% up as against its previous year. By the end of last year, China’s total direct investment abroad had stacked up to $51.7 billion.展开更多
Objective. To compare the embolization effects of intracranial aneurysms with mechanical detachable spirals (MDS) and with Guglielmi detachable coils (GDC).Methods. One hundred and twenty cases with 125 intracranial a...Objective. To compare the embolization effects of intracranial aneurysms with mechanical detachable spirals (MDS) and with Guglielmi detachable coils (GDC).Methods. One hundred and twenty cases with 125 intracranial aneurysms were embolized in Beijing Hospital from March 1995 to July 1999. Sixty - six aneurysms in 64 cases were embolized with MDS, 51 in 48 with GDC, and 8 in 8 with both MDS and GDC. Clinical data including sex, age, subarachnoid hemorrhage (SAH), Hunt & Hess grading, diameter and neck width of aneurysms, number and length of coils used per aneurysm, occlusive ratio, and complications were compared between MDS and GDC groups.Results. MDS and GDC groups were comparable (t-test or x2 -test, all P value > 0. 10) in terms of age, sex, diameter of aneurysms [ (8. 46 ± 3. 42) mm vs. (7. 38 ± 3. 45) mm], neck width [ (3. 49 ± 1. 50) mm vs. (3. 26 ± 1. 52) mm], coils number[ (4. 65 ± 3. 01) vs. (4. 24 ± 2. 65) ] and their length[ (460. 2 ± 398. 5) mm vs. (422. 9 ±387. 1) mm] used per aneurysm, occlusive ratio in aneurysms embolized ≥80% [ (95. 00% ± 6. 32% ) vs. (94. 19% ± 7. 63% ) ], mortality and permanent complications (7. 8% vs. 4. 2% ).Conclusions. MDS and GDC are all materials for embolization of intracranial aneurysms. MDS is less expensive, but more difficult to control and of propensity to complications while GDC is more compliant, easier to be used, safer, and have many alternative types for use as well as more extensive indications.展开更多
Twisted two-dimensional(2D)layered materials have attracted significant attention due to their twist angle-related superconductivity and moiréexciton phenomena.In twisted layered materials,supertwisted spirals ex...Twisted two-dimensional(2D)layered materials have attracted significant attention due to their twist angle-related superconductivity and moiréexciton phenomena.In twisted layered materials,supertwisted spirals exhibit multiple layers of continuous twisted structures,which give rise to their unique optoelectronic properties.Previous studies have primarily focused on the influence of conical non-Euclidean surfaces on the growth of twisted spirals,revealing their dominant role in determining the twist angle.However,few studies have systematically analyzed the additional factors influencing the variation of twist angles during the growth of such structures.In this work,we demonstrated the synthesis of supertwisted WS_(2) spirals on the edges of WS_(2) nanoribbons with nanoparticles,where the twist angle deviates from the theoretical value due to the additional influence of the nanoribbons during growth.Beyond the dominant role of nanoparticles in determining the twist angle of the spirals,we found that larger step heights or contact areas of the nanoribbons lead to larger twist angles.Furthermore,photoluminescence(PL)and Raman spectroscopy revealed the unique optical properties of the twisted spirals.PL spectra exhibited thickness-dependent abnormal variation in luminescence intensity,attributed to the decoupling and recoupling of interlayer interactions,while Raman spectra demonstrated the thickness-dependent and twist angle-dependent variations in the dominant atomic vibrations of interlayer van der Waals(vdW)interactions.These findings not only provide new insights into the regulation of twist angles in twisted spiral structures,but also contribute to a deeper understanding of the optical characteristics of twisted 2D layered materials,paving the way for their potential applications in various fields.展开更多
In CNC machining,the tool path planning of the cutter plays an important role.In this paper,we generate a space-filling and continuous tool path for free-form surface represented by the triangular mesh with a confined...In CNC machining,the tool path planning of the cutter plays an important role.In this paper,we generate a space-filling and continuous tool path for free-form surface represented by the triangular mesh with a confined scallop height.The tool path is constructed from connected Fermat spirals(CFS)but with fewer inflection points.Comparing with the newly developed CFS method,only about half of the number of inflection points are involved.Moreover,the kinematic constraints are simultaneously taken into account to increase the feedrates in machining.Finally,we use a micro-line trajectory technique to smooth the tool path.Experimental results and physical cutting tests are provided to illustrate and clarify our method.展开更多
Fibonacci number spiral patterns can be found in nature,particularly in plants,such as the sunflowers and phyllotaxis.Here,we demonstrated this pattern can be reproduced spontaneously within self-assembling peptide na...Fibonacci number spiral patterns can be found in nature,particularly in plants,such as the sunflowers and phyllotaxis.Here,we demonstrated this pattern can be reproduced spontaneously within self-assembling peptide nanofibril films.By high-temperature water vapor annealing of an amorphous film containing both peptide and cationic diamines,well-defined amyloid-like nanofibrils can be assembled spontaneously,during which the nanofibrils will hierarchically stack with each other following the Fibonacci number patterns.The formation of the patterns is a selftemplated process,which involves stepwise chiral amplification from the molecular scale to the nano-and micro-scales.Moreover,by controlling the diameter,length,and handedness of the nanofibrils,various complex hierarchical structures could be formed,including vertically aligned nanoarray,mesoscale helical bundles,Fibonacci number spirals,and then helical toroids.The results provide new insights into the chiral self-assembly of simple biological molecules,which can advance their applications in optics and templated synthesis.展开更多
Based on the Fluent numerical simulation method,this study systematically analyzed the structural parameters of the spiral tube heat exchanger and the influence of the external baffle on its heat transfer performance....Based on the Fluent numerical simulation method,this study systematically analyzed the structural parameters of the spiral tube heat exchanger and the influence of the external baffle on its heat transfer performance.The results show that when the equivalent diameter of the spiral tube increased from 16.68 to 21.23 mm,its surface heat transfer coefficient decreased from 22,040 to 17,230 W/m^(2)⋅K,and the outlet air temperature dropped from 822.3 to 807.3 K.However,the pressure loss decreased from 2.692 to 0.958 kPa.which reveals the contradiction between the heat transfer efficiency and the flow resistance.By adding a baffle to enhance the turbulent disturbance,the wall heat flux density is increased by 21.17%,the surface heat transfer coefficient is increased by 12.1%,and the outlet temperature is optimized,which verifies the significant improvement of the heat transfer performance by the countercurrent design.Comprehensive research shows that the collaborative optimization of spiral tube equivalent diameter parameters and baffle flow control is the key to improve the comprehensive performance of heat exchanger.Theresearch results provide a theoretical basis for energy-saving design of industrial heat exchangers.展开更多
Early fault detection for spiral bevel gears is crucial to ensure normal operation and prevent accidents.The harmonic components,excited by the time-varying mesh stiffness,always appear in measured vibration signal.Ho...Early fault detection for spiral bevel gears is crucial to ensure normal operation and prevent accidents.The harmonic components,excited by the time-varying mesh stiffness,always appear in measured vibration signal.How to extract the periodical impulses that indicate gear localized fault buried in the intensive noise and interfered by harmonics is a challenging task.In this paper,a novel Periodical Sparse-Assisted Decoupling(PSAD)method is proposed as an optimization problem to extract fault feature from noisy vibration signal.The PSAD method decouples the impulsive fault feature and harmonic components based on the sparse representation method.The sparsity within and across groups property and the periodicity of the fault feature are incorporated into the regularizer as the prior information.The nonconvex penalty is employed to highlight the sparsity of fault features.Meanwhile,the weight factor based on2norm of each group is constructed to strengthen the amplitude of fault feature.An iterative algorithm with Majorization-Minimization(MM)is derived to solve the optimization problem.Simulation study and experimental analysis confirm the performance of the proposed PSAD method in extracting and enhancing defect impulses from noisy signal.The suggested method surpasses other comparative methods in extracting and enhancing fault features.展开更多
In this paper, the phenomena of spirals are numerically presented by MmB scheme [1] for initial value problems of 2-D gas dynamics (gamma = 1.4), which include 2-D Riemann problems and continuous initial value problem...In this paper, the phenomena of spirals are numerically presented by MmB scheme [1] for initial value problems of 2-D gas dynamics (gamma = 1.4), which include 2-D Riemann problems and continuous initial value problems. The numerical results are well coincide with on the exact solution in [2] and the conjectures on solution structure in [3] for 2-D isentropic and adiabatic flows. In isentropic flow, for high speed rotation (v(0)/c(0) > root 2), there is a region of vacuum at the origin and for low speed rotation (v(0)/c(0) < root 2), there is no vacuum, and for adiabatic flow, the structure of spirals is also discussed.展开更多
Aminoglycosides are a widely used class of antibacterials renowned for their effectiveness and broad antimicrobial spectrum.However,their use leads to irreversible hearing damage by causing apoptosis of hair cells as ...Aminoglycosides are a widely used class of antibacterials renowned for their effectiveness and broad antimicrobial spectrum.However,their use leads to irreversible hearing damage by causing apoptosis of hair cells as their direct target.In addition,the hearing damage caused by aminoglycosides involves damage of spiral ganglion neurons upon exposure.To investigate the mechanisms underlying spiral ganglion neuron degeneration induced by aminoglycosides,we used a C57BL/6J mouse model treated with kanamycin.We found that the mice exhibited auditory deficits following the acute loss of outer hair cells.Spiral ganglion neurons displayed hallmarks of pyroptosis and exhibited progressive degeneration over time.Transcriptomic profiling of these neurons showed significant upregulation of genes associated with inflammation and immune response,particularly those related to the NLRP3 inflammasome.Activation of the canonical pyroptotic pathway in spiral ganglion neurons was observed,accompanied by infiltration of macrophages and the release of proinflammatory cytokines.Pharmacological intervention targeting NLRP3 using Mcc950 and genetic intervention using NLRP3 knockout ameliorated spiral ganglion neuron degeneration in the injury model.These findings suggest that NLRP3 inflammasome-mediated pyroptosis plays a role in aminoglycoside-induced spiral ganglion neuron degeneration.Inhibition of this pathway may offer a potential therapeutic strategy for treating sensorineural hearing loss by reducing spiral ganglion neuron degeneration.展开更多
Spiral pile foundations,as a promising type of foundation,are of significant importance for the development of offshore wind energy,particularly as it moves toward deeper waters.This study conducted a physical experim...Spiral pile foundations,as a promising type of foundation,are of significant importance for the development of offshore wind energy,particularly as it moves toward deeper waters.This study conducted a physical experiment on a three-spiral-pile jacket foundation under deep-buried sandy soil conditions.During the experiment,horizontal displacement was applied to the structure to thoroughly investigate the bearing characteristics of the three-spiral-pile jacket foundation.This study also focused on analyzing the bearing mechanisms of conventional piles compared with spiral piles with different numbers of blades.Three different working conditions were set up and compared,and key data,such as the horizontal bearing capacity,pile shaft axial force,and spiral blade soil pressure,were measured and analyzed.The results show the distinct impacts of the spiral blades on the compressed and tensioned sides of the foundation.Specifically,on the compressed side,the spiral blades effectively enhance the restraint of the soil on the pile foundation,whereas on the tensioned side,an excessive number of spiral blades can negatively affect the structural tensile performance to some extent.This study also emphasizes that the addition of blades to the side of a single pile is the most effective method for increasing the bearing capacity of the foundation.This research aims to provide design insights into improving the bearing capacity of the foundation.展开更多
Spiral bevel gears are critical transmission components,and are widely used in the aerospace field.This paper proposes a new multi-DOF envelope forming process for fabricating spiral bevel gears.Firstly,the multi-DOF ...Spiral bevel gears are critical transmission components,and are widely used in the aerospace field.This paper proposes a new multi-DOF envelope forming process for fabricating spiral bevel gears.Firstly,the multi-DOF envelope forming principle of spiral bevel gears is proposed.Secondly,the design methods for the envelope tool geometry and movement are proposed based on the envelope geometry and movement relationships.Thirdly,the metal flow and tooth filling laws are revealed through 3D FE simulation of the multi-DOF envelope forming process of a typical spiral bevel gear.Fourthly,a new method for separating the envelope tool and the formed spiral bevel gear with back taper tooth is proposed to avoid their interference.Finally,experiments on multi-DOF envelope forming of this typical spiral bevel gear are conducted using new heavy load multi-DOF envelope forming equipment.The simulation and experimental results show the feasibility of the proposed multi-DOF envelope forming process for fabricating spiral bevel gears with back taper tooth and the corresponding process design methods.展开更多
Photoinduced[2+2]cycloaddition of biomass-derived cycloolefin is a promising approach to synthesize high-energy bio-fuels,however,the conversion efficiency and selectivity are still low.Herein,we provide an acid-promo...Photoinduced[2+2]cycloaddition of biomass-derived cycloolefin is a promising approach to synthesize high-energy bio-fuels,however,the conversion efficiency and selectivity are still low.Herein,we provide an acid-promoted photocycloaddition approach to synthesize a new kind of spiral fuel from biomass-derived cyclohexanone (CHOE) and camphene (CPE).BrΦnsted acids show higher catalytic activity than Lewis acids,and acetic acid (HOAc) possesses the best catalytic performance,with CHOE conversion up to 99.1%.Meanwhile,the HOAc-catalytic effect has been confirmed for[2+2]photocycloaddition of other biomass-derived ketenes and olefins.The catalytic mechanism and dynamics have been investigated,and show that HOAc can bond with C=O groups of CHOE to form H–CHOE complex,which leads to higher light adsorption and longer triplet lifetime.Meanwhile,H–CHOE complex reduces the energy gap between CHOE LUMO and CPE HOMO,shortens the distance of ring-forming atoms,and then decreases the energy barrier (from 103.3 kcal mol^(-1)to 95.8 kcal mol^(-1)) of rate-limiting step.After hydrodeoxygenation,the targeted bio-spiral fuel shows high density of 0.992 g cm^(-3),high neat heat of combustion of 41.89 MJ L^(-1),low kinetic viscosity of 5.69 mm^(2)s^(-1)at 20℃,which is very promising to serve as high-performance aerospace fuel.展开更多
During high-speed rotation,the surface of aeronautic spiral bevel gears will generate significant pressure and viscous forces,which will cause a certain amount of windage power loss and reduce the efficiency of the tr...During high-speed rotation,the surface of aeronautic spiral bevel gears will generate significant pressure and viscous forces,which will cause a certain amount of windage power loss and reduce the efficiency of the transmission system.Based on the computational fluid dynamics,this paper analyzes the windage power loss of a single spiral bevel gear and a spiral bevel gear pair under oil injection lubrication.In addition,the shroud is used to suppress gear windage loss,and the clearance size and opening angle of the designed shroud are optimized.Finally,by comparing and analyzing the experimental results,the following conclusions were obtained:(1)For a single gear,the speed is the most important factor affecting windage loss,followed by the hand of spiral,and rotation direction;(2)For gear pairs,under oil injection lubrication,the input speed has the greatest impact on windage power loss,followed by the influence of oil injection port speed,temperature and oil injection port pressure;(3)Installing a shroud is an effective method to reduce windage power loss;(4)In the pure air phase,the smaller the clearance between the shroud and the gear surface,and the smaller the radial direction between the shroud and the shaft,the better the effect of reducing windage;(5)In the two-phase flow of oil and gas,it is necessary to design oil drainage holes on the shroud to ensure the smooth discharge of lubricating oil and improve the drag reduction effect.展开更多
1临床资料患儿,女,3岁,主因“发现右耳听力差3年”就诊。家长3年前发现患儿右耳听力差,站于右侧呼唤患儿反应迟钝,说话发声及面部表情正常。体格检查:双侧耳廓及外耳道未见明显异常。声导抗:双耳A型。声反射:左侧90 dB SPL,右侧未引出...1临床资料患儿,女,3岁,主因“发现右耳听力差3年”就诊。家长3年前发现患儿右耳听力差,站于右侧呼唤患儿反应迟钝,说话发声及面部表情正常。体格检查:双侧耳廓及外耳道未见明显异常。声导抗:双耳A型。声反射:左侧90 dB SPL,右侧未引出。行为测听:左侧听力正常,右侧极重度感音神经性听力下降。耳声发射(OAE):左侧正常,右侧全频未引出。展开更多
Optical field manipulation,an emerging frontier in photonics,demonstrates significant potential in biomedical microscopy,quantum state engineering,and micro-nano fabrication.To address the critical limitations of curr...Optical field manipulation,an emerging frontier in photonics,demonstrates significant potential in biomedical microscopy,quantum state engineering,and micro-nano fabrication.To address the critical limitations of current optical modulation technologies in achieving full-parameter precision control,we proposed a novel approach for dynamic azimuthal optical field modulation based on dual-spiral arrays.By designing spatially interleaved spiral structures with different initial radii while maintaining identical periodic parameters,we achieved continuous optical modulation spanning the full 0-2πrange in azimuthal field distribution.Through rigorous numerical simulations,we systematically established a quantitative correlation between the structural parameters and azimuthal optical field patterns,revealing,for the first time,a quasi-linear relationship between the radius difference and the resultant optical distribution.This theoretical framework advances our fundamental understanding of structured optical field manipulation as well as provides a new paradigm for programmable photonic device design,with distinct technical advantages in super-resolution imaging and optical tweezer systems.展开更多
Spiral galaxies are the most common type of galaxies in the universe,and most spiral galaxies contain a supermassive black hole in their center.However,thus far,the formation of spiral galaxies is still not fully unde...Spiral galaxies are the most common type of galaxies in the universe,and most spiral galaxies contain a supermassive black hole in their center.However,thus far,the formation of spiral galaxies is still not fully understood,and especially,what determines the number of spiral arms is still an open question as well.Here,inspired by fascinating spiral galaxies,we demonstrate that such a spiral-galaxy-shaped optical field can be generated by interference of a vortex wave and a trumpet wave.Interestingly,we show it is the topological charge of the vortex wave that determines the number of spiral arms in our model.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
In this paper,a 4×4 wideband linearly po-larization(LP)antenna array is proposed by using pla-nar dual-arm spiral structures.Wideband balun struc-tures,composed of microstrip line-fed coupling slots,are adopted t...In this paper,a 4×4 wideband linearly po-larization(LP)antenna array is proposed by using pla-nar dual-arm spiral structures.Wideband balun struc-tures,composed of microstrip line-fed coupling slots,are adopted to feed two dual-arms spiral structures with opposite phases.Then,by combining the left-and right-hand circular polarizations,a linearly polar-ization is achieved.The proposed antenna has a wide operating bandwidth due to the wideband nature of the spiral structure.Simulated results show that the an-tenna element can achieve a 68.73%impedance band-width and a maximum gain of 6.64 dBi within 19.44–38.83 GHz.A 4×4 array prototype is designed to verify the concept.Measured results show that an impedance bandwidth of 63.73%is obtained.The pro-posed array has the merits of a wide bandwidth,a low profile,a low cost,and a small size,which is promis-ing for the application in millimeter wave wireless sys-tems.展开更多
基金funded by the National Natural Science Foundation of China (Grant Nos.41306003 and 41430963)the Fundamental Research Funds for Central Universities (Grant Nos.0905-841313038,1100-841262028 and 0905-201462003)+1 种基金the China Postdoctoral Science Foundation (Grant No.2013M531647)the Natural Science Foundation of Shandong (Grant No.BS2013HZ015)
文摘Horizontal velocity spirals with a clockwise rotation(downward looking) rate of 1.7?m^(-1), on average, were observed in the western and northern Yellow Sea from December 2006 to February 2007. With the observed thermal wind relation,the beta-spiral theory was used to explain the dynamics of spirals. It was found that the horizontal diffusion of geostrophic vortex stretching is likely to be a major mechanism for generating geostrophic spirals. Vertical advection associated with surface/bottom Ekman pumping and topography-induced upwelling is too weak to support these spirals. Strong wind stirring and large heat loss in wintertime lead to weak stratification and diminish the effects of vertical advection. The cooling effect and vertical diffusion are offset by an overwhelming contribution of horizontal diffusion in connection with vortex stretching. The Richardson number-dependent vertical eddy diffusivity reaches a magnitude of 10^(-4) m^2 s^(-1) on average. An eddy diffusivity of 2870 m^2 s^(-1) is required for dynamic balance by estimating the residual term. This obtained value of 10-4 m^2 s^(-1) is in good agreement with the estimation in terms of observed eddy activities. The suppressed and unsuppressed diffusivities in the observation region are 2752 and 2881 m^2 s^(-1), respectively, which supports a closed budget for velocity rotation.
文摘The spiral has been studied for the first time in the book “About the spirals”, by Archimedes （Greece, 287-212 BC）. In America, the design of spirals seems to have been used previous to Archimedes＇ time, although in the Northwest of Argentina the appearance of this figure in ceramics can be dated between the years 800 and 1,400 （AD）. The spiral is found in cave paintings, in pumpkin carvings and in pottery, particularly those painted inside of plates （pucos in Quechua language）.There can be seen simple linear spirals, double spirals and spirals filled with squares, spirals in two, facing each other symmetrically, as well as spirals joined to bodies of animals. The number of spires detected in the largest spiral is 12, a number of evidently sacred characteristics. When there are several spirals in an earthenware vessel, it can be seen that all of them spin to the same side whether it is clockwise or not. This could have been caused by the predominance of the use of either one hand or the other by the ancient artist. This paper is produced with computer methods used to design spirals in the computer, either Archimedes or the logarithmic ones. Finally, the book： “Man and his symbols” of the psychiatrist Carl Gustav Jung （1875-1961） help to understand this congruencies. In this paper, Mathematics is complemented with the Archeology of art and Psychology.
文摘The source from MOC (Ministry of Commerce) releases that China’s outbound investment hit $6,920 million in 2005, rising by 53.6% while there were 1,067 new Chinese overseas operations as approved by MOC in 2005, 28.7% up as against its previous year. By the end of last year, China’s total direct investment abroad had stacked up to $51.7 billion.
基金This work was originally published in the Chinese Journal of Neuro-surgery (2001 17(2): 87-90) in Chinese.
文摘Objective. To compare the embolization effects of intracranial aneurysms with mechanical detachable spirals (MDS) and with Guglielmi detachable coils (GDC).Methods. One hundred and twenty cases with 125 intracranial aneurysms were embolized in Beijing Hospital from March 1995 to July 1999. Sixty - six aneurysms in 64 cases were embolized with MDS, 51 in 48 with GDC, and 8 in 8 with both MDS and GDC. Clinical data including sex, age, subarachnoid hemorrhage (SAH), Hunt & Hess grading, diameter and neck width of aneurysms, number and length of coils used per aneurysm, occlusive ratio, and complications were compared between MDS and GDC groups.Results. MDS and GDC groups were comparable (t-test or x2 -test, all P value > 0. 10) in terms of age, sex, diameter of aneurysms [ (8. 46 ± 3. 42) mm vs. (7. 38 ± 3. 45) mm], neck width [ (3. 49 ± 1. 50) mm vs. (3. 26 ± 1. 52) mm], coils number[ (4. 65 ± 3. 01) vs. (4. 24 ± 2. 65) ] and their length[ (460. 2 ± 398. 5) mm vs. (422. 9 ±387. 1) mm] used per aneurysm, occlusive ratio in aneurysms embolized ≥80% [ (95. 00% ± 6. 32% ) vs. (94. 19% ± 7. 63% ) ], mortality and permanent complications (7. 8% vs. 4. 2% ).Conclusions. MDS and GDC are all materials for embolization of intracranial aneurysms. MDS is less expensive, but more difficult to control and of propensity to complications while GDC is more compliant, easier to be used, safer, and have many alternative types for use as well as more extensive indications.
基金the National Natural Science Foundation of China(No.52273252).
文摘Twisted two-dimensional(2D)layered materials have attracted significant attention due to their twist angle-related superconductivity and moiréexciton phenomena.In twisted layered materials,supertwisted spirals exhibit multiple layers of continuous twisted structures,which give rise to their unique optoelectronic properties.Previous studies have primarily focused on the influence of conical non-Euclidean surfaces on the growth of twisted spirals,revealing their dominant role in determining the twist angle.However,few studies have systematically analyzed the additional factors influencing the variation of twist angles during the growth of such structures.In this work,we demonstrated the synthesis of supertwisted WS_(2) spirals on the edges of WS_(2) nanoribbons with nanoparticles,where the twist angle deviates from the theoretical value due to the additional influence of the nanoribbons during growth.Beyond the dominant role of nanoparticles in determining the twist angle of the spirals,we found that larger step heights or contact areas of the nanoribbons lead to larger twist angles.Furthermore,photoluminescence(PL)and Raman spectroscopy revealed the unique optical properties of the twisted spirals.PL spectra exhibited thickness-dependent abnormal variation in luminescence intensity,attributed to the decoupling and recoupling of interlayer interactions,while Raman spectra demonstrated the thickness-dependent and twist angle-dependent variations in the dominant atomic vibrations of interlayer van der Waals(vdW)interactions.These findings not only provide new insights into the regulation of twist angles in twisted spiral structures,but also contribute to a deeper understanding of the optical characteristics of twisted 2D layered materials,paving the way for their potential applications in various fields.
基金supported by Beijing Natural Science Foundation under Grant Z190004National Key Research and Development Program of China under Grant 2020YFA0713703,NSFC(Nos.11688101,61872332)and Fundamental Research Funds for the Central Universities.
文摘In CNC machining,the tool path planning of the cutter plays an important role.In this paper,we generate a space-filling and continuous tool path for free-form surface represented by the triangular mesh with a confined scallop height.The tool path is constructed from connected Fermat spirals(CFS)but with fewer inflection points.Comparing with the newly developed CFS method,only about half of the number of inflection points are involved.Moreover,the kinematic constraints are simultaneously taken into account to increase the feedrates in machining.Finally,we use a micro-line trajectory technique to smooth the tool path.Experimental results and physical cutting tests are provided to illustrate and clarify our method.
基金supported by the National Natural Science Foundation of China(21621004 and 22078239)Tianjin Development Program for Innovation and Entrepreneurship(2018)the State Key Laboratory of Chemical Engineering(SKL-Ch E-20Z04 and SKL-Ch E-21T03)。
文摘Fibonacci number spiral patterns can be found in nature,particularly in plants,such as the sunflowers and phyllotaxis.Here,we demonstrated this pattern can be reproduced spontaneously within self-assembling peptide nanofibril films.By high-temperature water vapor annealing of an amorphous film containing both peptide and cationic diamines,well-defined amyloid-like nanofibrils can be assembled spontaneously,during which the nanofibrils will hierarchically stack with each other following the Fibonacci number patterns.The formation of the patterns is a selftemplated process,which involves stepwise chiral amplification from the molecular scale to the nano-and micro-scales.Moreover,by controlling the diameter,length,and handedness of the nanofibrils,various complex hierarchical structures could be formed,including vertically aligned nanoarray,mesoscale helical bundles,Fibonacci number spirals,and then helical toroids.The results provide new insights into the chiral self-assembly of simple biological molecules,which can advance their applications in optics and templated synthesis.
基金supported by the Jing-Jin-Ji Regional Integrated Environmental Improvement-National Science and Technology Major Project(No.2024ZD1200400).
文摘Based on the Fluent numerical simulation method,this study systematically analyzed the structural parameters of the spiral tube heat exchanger and the influence of the external baffle on its heat transfer performance.The results show that when the equivalent diameter of the spiral tube increased from 16.68 to 21.23 mm,its surface heat transfer coefficient decreased from 22,040 to 17,230 W/m^(2)⋅K,and the outlet air temperature dropped from 822.3 to 807.3 K.However,the pressure loss decreased from 2.692 to 0.958 kPa.which reveals the contradiction between the heat transfer efficiency and the flow resistance.By adding a baffle to enhance the turbulent disturbance,the wall heat flux density is increased by 21.17%,the surface heat transfer coefficient is increased by 12.1%,and the outlet temperature is optimized,which verifies the significant improvement of the heat transfer performance by the countercurrent design.Comprehensive research shows that the collaborative optimization of spiral tube equivalent diameter parameters and baffle flow control is the key to improve the comprehensive performance of heat exchanger.Theresearch results provide a theoretical basis for energy-saving design of industrial heat exchangers.
基金supported by the National Science Foundationof China(Nos.52305127 and 52475130)。
文摘Early fault detection for spiral bevel gears is crucial to ensure normal operation and prevent accidents.The harmonic components,excited by the time-varying mesh stiffness,always appear in measured vibration signal.How to extract the periodical impulses that indicate gear localized fault buried in the intensive noise and interfered by harmonics is a challenging task.In this paper,a novel Periodical Sparse-Assisted Decoupling(PSAD)method is proposed as an optimization problem to extract fault feature from noisy vibration signal.The PSAD method decouples the impulsive fault feature and harmonic components based on the sparse representation method.The sparsity within and across groups property and the periodicity of the fault feature are incorporated into the regularizer as the prior information.The nonconvex penalty is employed to highlight the sparsity of fault features.Meanwhile,the weight factor based on2norm of each group is constructed to strengthen the amplitude of fault feature.An iterative algorithm with Majorization-Minimization(MM)is derived to solve the optimization problem.Simulation study and experimental analysis confirm the performance of the proposed PSAD method in extracting and enhancing defect impulses from noisy signal.The suggested method surpasses other comparative methods in extracting and enhancing fault features.
文摘In this paper, the phenomena of spirals are numerically presented by MmB scheme [1] for initial value problems of 2-D gas dynamics (gamma = 1.4), which include 2-D Riemann problems and continuous initial value problems. The numerical results are well coincide with on the exact solution in [2] and the conjectures on solution structure in [3] for 2-D isentropic and adiabatic flows. In isentropic flow, for high speed rotation (v(0)/c(0) > root 2), there is a region of vacuum at the origin and for low speed rotation (v(0)/c(0) < root 2), there is no vacuum, and for adiabatic flow, the structure of spirals is also discussed.
基金supported by the National Natural Science Foundation of China,Nos.81800919(to YX),82171140(to PW)the International Cooperation and Exchange of the National Natural Science Foundation of China,Nos.82020108008(to HS),81720108010(to SY).
文摘Aminoglycosides are a widely used class of antibacterials renowned for their effectiveness and broad antimicrobial spectrum.However,their use leads to irreversible hearing damage by causing apoptosis of hair cells as their direct target.In addition,the hearing damage caused by aminoglycosides involves damage of spiral ganglion neurons upon exposure.To investigate the mechanisms underlying spiral ganglion neuron degeneration induced by aminoglycosides,we used a C57BL/6J mouse model treated with kanamycin.We found that the mice exhibited auditory deficits following the acute loss of outer hair cells.Spiral ganglion neurons displayed hallmarks of pyroptosis and exhibited progressive degeneration over time.Transcriptomic profiling of these neurons showed significant upregulation of genes associated with inflammation and immune response,particularly those related to the NLRP3 inflammasome.Activation of the canonical pyroptotic pathway in spiral ganglion neurons was observed,accompanied by infiltration of macrophages and the release of proinflammatory cytokines.Pharmacological intervention targeting NLRP3 using Mcc950 and genetic intervention using NLRP3 knockout ameliorated spiral ganglion neuron degeneration in the injury model.These findings suggest that NLRP3 inflammasome-mediated pyroptosis plays a role in aminoglycoside-induced spiral ganglion neuron degeneration.Inhibition of this pathway may offer a potential therapeutic strategy for treating sensorineural hearing loss by reducing spiral ganglion neuron degeneration.
基金The National Natural Science Foundation of China(No.52171274).
文摘Spiral pile foundations,as a promising type of foundation,are of significant importance for the development of offshore wind energy,particularly as it moves toward deeper waters.This study conducted a physical experiment on a three-spiral-pile jacket foundation under deep-buried sandy soil conditions.During the experiment,horizontal displacement was applied to the structure to thoroughly investigate the bearing characteristics of the three-spiral-pile jacket foundation.This study also focused on analyzing the bearing mechanisms of conventional piles compared with spiral piles with different numbers of blades.Three different working conditions were set up and compared,and key data,such as the horizontal bearing capacity,pile shaft axial force,and spiral blade soil pressure,were measured and analyzed.The results show the distinct impacts of the spiral blades on the compressed and tensioned sides of the foundation.Specifically,on the compressed side,the spiral blades effectively enhance the restraint of the soil on the pile foundation,whereas on the tensioned side,an excessive number of spiral blades can negatively affect the structural tensile performance to some extent.This study also emphasizes that the addition of blades to the side of a single pile is the most effective method for increasing the bearing capacity of the foundation.This research aims to provide design insights into improving the bearing capacity of the foundation.
基金the National Science and Technology Major Project of China(No.2019-VII0017e0158)the National Natural Science Foundation of China(No.U21A20131)+1 种基金the Industry-University Research Cooperation Project,China(No.HFZL2020CXY025)the National Key Laboratory of Science and Technology on Helicopter Transmission,China(No.HTL-O-21G05).
文摘Spiral bevel gears are critical transmission components,and are widely used in the aerospace field.This paper proposes a new multi-DOF envelope forming process for fabricating spiral bevel gears.Firstly,the multi-DOF envelope forming principle of spiral bevel gears is proposed.Secondly,the design methods for the envelope tool geometry and movement are proposed based on the envelope geometry and movement relationships.Thirdly,the metal flow and tooth filling laws are revealed through 3D FE simulation of the multi-DOF envelope forming process of a typical spiral bevel gear.Fourthly,a new method for separating the envelope tool and the formed spiral bevel gear with back taper tooth is proposed to avoid their interference.Finally,experiments on multi-DOF envelope forming of this typical spiral bevel gear are conducted using new heavy load multi-DOF envelope forming equipment.The simulation and experimental results show the feasibility of the proposed multi-DOF envelope forming process for fabricating spiral bevel gears with back taper tooth and the corresponding process design methods.
基金the support from National Key R&D Program of China (2021YFC2103704)the National Natural Science Foundation of China (22222808)+4 种基金the Natural Science Foundation of Shandong Province (ZR2023QB152)the Youth Innovation Team Plan of Shandong Province (2022KJ270)the China National Postdoctoral Program for Innovative Talents (BX20240251)the Aeronautical Science Foundation of China (2023Z073048003)the Haihe Laboratory of Sustainable Chemical Transformations。
文摘Photoinduced[2+2]cycloaddition of biomass-derived cycloolefin is a promising approach to synthesize high-energy bio-fuels,however,the conversion efficiency and selectivity are still low.Herein,we provide an acid-promoted photocycloaddition approach to synthesize a new kind of spiral fuel from biomass-derived cyclohexanone (CHOE) and camphene (CPE).BrΦnsted acids show higher catalytic activity than Lewis acids,and acetic acid (HOAc) possesses the best catalytic performance,with CHOE conversion up to 99.1%.Meanwhile,the HOAc-catalytic effect has been confirmed for[2+2]photocycloaddition of other biomass-derived ketenes and olefins.The catalytic mechanism and dynamics have been investigated,and show that HOAc can bond with C=O groups of CHOE to form H–CHOE complex,which leads to higher light adsorption and longer triplet lifetime.Meanwhile,H–CHOE complex reduces the energy gap between CHOE LUMO and CPE HOMO,shortens the distance of ring-forming atoms,and then decreases the energy barrier (from 103.3 kcal mol^(-1)to 95.8 kcal mol^(-1)) of rate-limiting step.After hydrodeoxygenation,the targeted bio-spiral fuel shows high density of 0.992 g cm^(-3),high neat heat of combustion of 41.89 MJ L^(-1),low kinetic viscosity of 5.69 mm^(2)s^(-1)at 20℃,which is very promising to serve as high-performance aerospace fuel.
基金Supported by National Natural Science Foundation of China(Grant Nos.51175422,61973011)Shaanxi Provincial Natural Science Basic Research Plan of China(Grant No.2022JM-195)+1 种基金Fundamental Research Funds for the Central Universities of Chinathe Research Start-up Funds of Hangzhou International Innovation Institute of Beihang University(Grant No.2024KQ036)。
文摘During high-speed rotation,the surface of aeronautic spiral bevel gears will generate significant pressure and viscous forces,which will cause a certain amount of windage power loss and reduce the efficiency of the transmission system.Based on the computational fluid dynamics,this paper analyzes the windage power loss of a single spiral bevel gear and a spiral bevel gear pair under oil injection lubrication.In addition,the shroud is used to suppress gear windage loss,and the clearance size and opening angle of the designed shroud are optimized.Finally,by comparing and analyzing the experimental results,the following conclusions were obtained:(1)For a single gear,the speed is the most important factor affecting windage loss,followed by the hand of spiral,and rotation direction;(2)For gear pairs,under oil injection lubrication,the input speed has the greatest impact on windage power loss,followed by the influence of oil injection port speed,temperature and oil injection port pressure;(3)Installing a shroud is an effective method to reduce windage power loss;(4)In the pure air phase,the smaller the clearance between the shroud and the gear surface,and the smaller the radial direction between the shroud and the shaft,the better the effect of reducing windage;(5)In the two-phase flow of oil and gas,it is necessary to design oil drainage holes on the shroud to ensure the smooth discharge of lubricating oil and improve the drag reduction effect.
文摘1临床资料患儿,女,3岁,主因“发现右耳听力差3年”就诊。家长3年前发现患儿右耳听力差,站于右侧呼唤患儿反应迟钝,说话发声及面部表情正常。体格检查:双侧耳廓及外耳道未见明显异常。声导抗:双耳A型。声反射:左侧90 dB SPL,右侧未引出。行为测听:左侧听力正常,右侧极重度感音神经性听力下降。耳声发射(OAE):左侧正常,右侧全频未引出。
文摘Optical field manipulation,an emerging frontier in photonics,demonstrates significant potential in biomedical microscopy,quantum state engineering,and micro-nano fabrication.To address the critical limitations of current optical modulation technologies in achieving full-parameter precision control,we proposed a novel approach for dynamic azimuthal optical field modulation based on dual-spiral arrays.By designing spatially interleaved spiral structures with different initial radii while maintaining identical periodic parameters,we achieved continuous optical modulation spanning the full 0-2πrange in azimuthal field distribution.Through rigorous numerical simulations,we systematically established a quantitative correlation between the structural parameters and azimuthal optical field patterns,revealing,for the first time,a quasi-linear relationship between the radius difference and the resultant optical distribution.This theoretical framework advances our fundamental understanding of structured optical field manipulation as well as provides a new paradigm for programmable photonic device design,with distinct technical advantages in super-resolution imaging and optical tweezer systems.
基金National Natural Science Foundation of China(12174047,12574353)。
文摘Spiral galaxies are the most common type of galaxies in the universe,and most spiral galaxies contain a supermassive black hole in their center.However,thus far,the formation of spiral galaxies is still not fully understood,and especially,what determines the number of spiral arms is still an open question as well.Here,inspired by fascinating spiral galaxies,we demonstrate that such a spiral-galaxy-shaped optical field can be generated by interference of a vortex wave and a trumpet wave.Interestingly,we show it is the topological charge of the vortex wave that determines the number of spiral arms in our model.
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 in part by the National Natural Science Foundation of China under Grant 62131008the Fundamental Research Funds for the Central Universities 2242022k60003.
文摘In this paper,a 4×4 wideband linearly po-larization(LP)antenna array is proposed by using pla-nar dual-arm spiral structures.Wideband balun struc-tures,composed of microstrip line-fed coupling slots,are adopted to feed two dual-arms spiral structures with opposite phases.Then,by combining the left-and right-hand circular polarizations,a linearly polar-ization is achieved.The proposed antenna has a wide operating bandwidth due to the wideband nature of the spiral structure.Simulated results show that the an-tenna element can achieve a 68.73%impedance band-width and a maximum gain of 6.64 dBi within 19.44–38.83 GHz.A 4×4 array prototype is designed to verify the concept.Measured results show that an impedance bandwidth of 63.73%is obtained.The pro-posed array has the merits of a wide bandwidth,a low profile,a low cost,and a small size,which is promis-ing for the application in millimeter wave wireless sys-tems.
