This research was conducted to study the performances of the heat and multilayer reflection insulators used for buildings in South Korea to realize eco-friendly, low-energy-consumption, green construction, and to cont...This research was conducted to study the performances of the heat and multilayer reflection insulators used for buildings in South Korea to realize eco-friendly, low-energy-consumption, green construction, and to contribute to energy consumption reduction in buildings and to the nation＇s greenhouse gas emission reduction policy （targeting 30% reduction compared to BAUCousiness as usual） by 2020）. The heat insulation performance test is about the temperatures on surfaces of test piece. The high air temperature and the low air temperature were measured to determine the overall heat transfer coefficient and thermal conductivity. The conclusions are drawn that the heat transmission coefficients for each type of existing reflection insulator are： A-1 （0.045 W/（m-K））, A-2 （0.031 W/（m.K））, A-3 （0.042 W/（m.K））, A-4 （0.078 W/（m.K））, and the average heat conductivity is 0.049 W/（m-K）; The heat conductivity for each type of Styrofoam insulator are 0.030 W/（m.K） for B-l, 0.032 W/（m-K） for B-2, 0.037 W/（m＇K） for B-3, 0.037 W/（m.K） for B-4, and the average heat conductivity is 0.035 W/（m＇K） regardless of the thickness of the insulator; The heat conductivity values of the multilayer reflection insulators are converted based on the thickness and type C-1 （0.020 W/（m.K））, C-2 （0.018 W/（m.K））, C-3 （0.016 W/（m.K））, and C-4 （0.012 W/（m.K））; The multilayer reflection insulator keeps the indoor-side surface temperature high （during winter） or low （in summer）, enhances the comfort of the building occupants, and conducts heating and moisture resistance to prevent dew condensation on the glass-outer-wall surface.展开更多
The collision between the Indian and Asian plates uplifted the Himalayan-Tibetan Plateau,thickening and expanding the crust.It is a scientific mystery of global concern as how the two continents collide and how the co...The collision between the Indian and Asian plates uplifted the Himalayan-Tibetan Plateau,thickening and expanding the crust.It is a scientific mystery of global concern as how the two continents collide and how the continent-continent collision deforms the continent.Deep seismic reflection profile detection is one of the most effective ways to unlock this scientific mystery.For more than 20 years using this technology,we have detected fine structures of the thick crust of the Tibetan plateau after overcoming technical bottlenecks to access the lower crust and Moho thus revealing the continental collision processes.This paper systematically summarizes the deep behaviors of the India-Asia collision and subduction beneath the Tibetan Plateau,from south to north,east to west and further into the hinterland of the plateau.The Indian crust undergoes underthrusting beneath the Himalayan orogenic belt on the southern margin of the plateau.Meanwhile,the lithosphere of the Alxa block in the Asian plate subducts southward beneath the Qilian Mountain in the north of the plateau,driving the northward overthrusting of the Qilian crust.Additionally,the Tarim and West Kunlun blocks undergo face-to-face collision in the northwestern margin of the plateau.In the easternmost part of the plateau,the Longriba fault,instead of the Longmen Shan fault zone,marks the western margin of the Yangtze block.It is also seismically evidenced that the Moho geometry in the plateaus hinterland appears thin and flat,indicating lithospheric collapse and extrusion.Multiple deep reflection profiles revealed the collisional behavior under the Yalung-Zangbo suture zone and longitudinal variation in subducting geometry of the Indian crust from west to the east.In the middle of the suture zone,it shows a decoupling between the upper and lower crusts of the Indian plate,where the upper crust undergoes a northward overthrusting while the lower one experiences a northward underthrusting.It is also seismically evidenced a down-and southward crustal duplexing of the subducting Indian crust thickening the northern Himalayas,leaving over a thinning subducting lower crust of the Indian slab.The subduction front of the Indian crust collides with the lower crust of the Asian plate at the mantle depth.A near-vertical collision boundary is seen between the Gangdese batholith and the Tethyan Himalayas,where the Gangdese batholith shows almost transparent weak reflections in the lower crust with localized bright spot reflection that indicates partial melting.Additionally,the near-flat Moho geometry implies an extensional tectonic environment of the southern margin of the Asian plate.展开更多
Altun fault is regarded as a large\|scale sinistral strike\|slip fault, it is composed of several faults with the different character, and there is a special geological structure in the fault belt, and they constitute...Altun fault is regarded as a large\|scale sinistral strike\|slip fault, it is composed of several faults with the different character, and there is a special geological structure in the fault belt, and they constitute the northwestern margin fault belt of the Qinghai\|Tibetan plateau. In order to investigate the deep crust structure in the Altun region, layers which Tarim lithosphere subducted beneath the Qinghai\|Tibetan plateau, the forward structure of the subduction plate and the scale of the plate subduction, a deep seismic reflection profile was designed. Data collection work of the deep seismic reflection profile across Altun fault was completed during 24/8/1999 to 25/9/1999. The profile locates in Qiemo county, Xinjiang Uygur Autonomous Region, the southern end of the profile stretches into Altun Mountains, the northern end locates in the Tarim desert margin. The profile is nearly SN trending and crosses the main Altun fault. The profile totally is 145km long, time record is 30 seconds, the smallest explosive amount is 72～100kg, the biggest explosive amount reaches 200～300kg, the explosive distance is 800m, and detectors are laid at a 50m distance.展开更多
The electric-controlled metasurface antenna array(ECMSAA)with ultra-wideband frequency reconfigurable reflection suppression is proposed and realized.Firstly,an electriccontrolled metasurface with ultra-wideband frequ...The electric-controlled metasurface antenna array(ECMSAA)with ultra-wideband frequency reconfigurable reflection suppression is proposed and realized.Firstly,an electriccontrolled metasurface with ultra-wideband frequency reconfigurable in-phase reflection characteristics is designed.The element of the ECMSAA is constructed by loading the single electric-controlled metasurface unit on the conventional patch antenna element.The radiation properties of the conventional patch antenna and the reflection performance of electric-controlled metasurface are maintained when the antenna and the metasurface are integrated.Thus,the ECMSAA elements have excellent radiation properties and ultra-wideband frequency reconfigurable in-phase reflection characteristics simultaneously.To take a further step,a 6×10 ECMSAA is realized based on the designed metasurface antenna element.Simulated and measured results prove that the reflection of the ECMSAA is dynamically suppressed in the P and L bands.Meanwhile,high-gain and multi-polarization radiation properties of the ECMSAA are achieved.This design method not only realizes the frequency reconfigurable reflection suppression of the antenna array in the ultra-wide frequency band but also provides a way to develop an intelligent low-scattering antenna.展开更多
The current work is an extension of the nonlocal elasticity theory to fractional order thermo-elasticity in semiconducting nanostructure medium with voids.The analysis is made on the reflection phenomena in context of...The current work is an extension of the nonlocal elasticity theory to fractional order thermo-elasticity in semiconducting nanostructure medium with voids.The analysis is made on the reflection phenomena in context of three-phase-lag thermo-elastic model.It is observed that,four-coupled longitudinal waves and an independent shear vertical wave exist in the medium which is dispersive in nature.It is seen that longitudinal waves are damped,and shear wave is un-damped when angular frequency is less than the cut-off frequency.The voids,thermal and non-local parameter affect the dilatational waves whereas shear wave is only depending upon non-local parameter.It is found that reflection coefficients are affected by nonlocal and fractional order parameters.Reflection coefficients are calculated analytically and computed numerically for a material,silicon and discussed graphically in details.The results for local(classical)theory are obtained as a special case.The study may be useful in semiconductor nanostructure,geology and seismology in addition to semiconductor nanostructure devices.展开更多
Reflection engineering plays an important role in optics.For conventional approaches,the reflection tuning is quite challenging in a loss-free component.Therefore,a simple approach to tune the reflection is highly des...Reflection engineering plays an important role in optics.For conventional approaches,the reflection tuning is quite challenging in a loss-free component.Therefore,a simple approach to tune the reflection is highly desired in plenty of applications.In this paper,we propose a new design of metasurface with just one single layer dielectric structure to tune the reflection of an interface by destructive interference in a subwavelength scale.By arranging the orientation of nano-antennas,the reflectivity tuning from 20%to 90%can be achieved at the wavelength of 1550 nm.Moreover,such reflectivity tuning of the designed metasurface works at the tunable wavelength from1500 nm to 1600 nm.This ultra-thin solution can achieve similar performance as the traditional bulky components without diffraction orders,while the design and fabrication are much simple and flexible.The ultra-thin and tunable properties indicate the great potentials of this method to be applied in laser fabrication,optical communication and optical integration.展开更多
Specific to the reflected light problem on the surface of transparent body,the polarization characteristics of the reflection region are analyzed,and a polarization characterization model combining the reflection and ...Specific to the reflected light problem on the surface of transparent body,the polarization characteristics of the reflection region are analyzed,and a polarization characterization model combining the reflection and transmission effects is established.On the basis of the polarization characteristic analysis,the minimum value of normalized cross-correlation(NCC)coefficient between transmission and reflection images is solved through the gradient descent method,and their polarization degrees under the minimum correlation are acquired.According to the distribution relations of the transmitted and reflected lights in perpendicular and parallel directions,reflection separation is realized via the polarized orthogonality difference algorithm based on the degree of reflection polarization and the degree of transmission polarization.展开更多
The electromagnetic surface antenna array(EMSAA)has been proposed for obtaining reflection suppression and excellent radiation simultaneously.The antenna with rectangular radiation patch is used to design anisotropic ...The electromagnetic surface antenna array(EMSAA)has been proposed for obtaining reflection suppression and excellent radiation simultaneously.The antenna with rectangular radiation patch is used to design anisotropic electromagnetic surface.Preternatural reflection characteristics of the element antenna can be tailored depending on the incident polarizations.EMSAA can be constructed by using single structured element antenna with 90° rotation and orthometric arrangement.This orthometric arrangement of EMSAA is helpful to achieve reflection suppression and excellent radiation.The simulated results show that the reflection of EMSAA is suppressed from 5.0 GHz to 8.0 GHz with peak reduction of 12.3 dB.The linear-and circular-polarized radiation properties of EMSAA are obtained and the maximum gain is 14.3 dBi.The measured results are consistent with the simulation results.The results demonstrate that the reflection suppression and excellent radiation are achieved simultaneously.Such design of EMSAA will open the path for integrating antenna fields and electromagnetic surface(EMS)fields.展开更多
The influence of the most important parameters on the service life of reinforced asphalt overlay with geogrid materials in bending mode was examined by employing the Taguchi method and analysis of variance techniques....The influence of the most important parameters on the service life of reinforced asphalt overlay with geogrid materials in bending mode was examined by employing the Taguchi method and analysis of variance techniques. The objectives of this experiment was to investigate the effects of grid stiffness, tensile strength, coating type, amount of tack coat, overlay thickness, crack width and stiffnesses of asphalt overlay and existing asphalt concrete on propagation of the reflection cracking. Results indicate that the stiffnesses of cracked layer and overlay are the main significant factors that can directly improve the service life of an overlay against the reflection cracking. Generally, glass grid is more effective in reinforced overlay than polyester grid. Effect of crack width of the existing layer is significant when its magnitude increases from 6 to 9 mm.展开更多
The radiative properties of three different materials surfaces with one-dimensional microscale random roughness were obtained with the finite difference time domain method(FDTD) and near-to-far-field transformation.Th...The radiative properties of three different materials surfaces with one-dimensional microscale random roughness were obtained with the finite difference time domain method(FDTD) and near-to-far-field transformation.The surface height conforms to the Gaussian probability density function distribution.Various computational modeling issues that affect the accuracy of the predicted properties were discussed.The results show that,for perfect electric conductor(PEC) surfaces,as the surface roughness increases,the magnitude of the spike reduces and eventually the spike disappears,and also as the ratio of root mean square roughness to the surface correlation distance increases,the retroreflection becomes evident.The predicted values of FDTD solutions are in good agreement with the ray tracing and integral equation solutions.The overall trend of bidirectional reflection distribution function(BRDF) of PEC surfaces and silicon surfaces is the same,but the silicon's is much less than the former's.The BRDF difference from two polarization modes for the gold surfaces is little for smaller wavelength,but it is much larger for the longer wavelength and the FDTD simulation results agree well with the measured data.In terms of PEC surfaces,as the incident angle increases,the reflectivity becomes more specular.展开更多
It is always a challenging issue for radar systems to estimate the height of a low-angle target in the multipath propagation environment.The highly deterministic maximum likelihood estimator has a high accuracy,but th...It is always a challenging issue for radar systems to estimate the height of a low-angle target in the multipath propagation environment.The highly deterministic maximum likelihood estimator has a high accuracy,but the errors of the ground reflection coefficient and the reflecting surface height have serious influence on the method.In this paper,a robust es-timation method with less computation burden is proposed based on the compound reflection coefficient multipath model for low-angle targets.The compound reflection coefficient is es-timated from the received data of the array and then a one-di-mension generalized steering vector is constructed to estimate the target height.The algorithm is robust to the reflecting sur-face height error and the ground reflection coefficient error.Fi-nally,the experiment and simulation results demonstrate the validity of the proposed method.展开更多
Being the core of the Songpan-Ganze block,Zoig(?)Basin is a favorable zone of oil and gas exploration.And it not only is the important deposition area of the northern Songpan-Garze in the Middle-Late Triassic,but also...Being the core of the Songpan-Ganze block,Zoig(?)Basin is a favorable zone of oil and gas exploration.And it not only is the important deposition area of the northern Songpan-Garze in the Middle-Late Triassic,but also impacts on the formation and evolution of the structural belt.展开更多
In this study,polyacrylic acid(PAA)films were employed as a model system,and a series of PAA films with tunable water wettability was systematically prepared by varying molecular weight and curing temperature.Using at...In this study,polyacrylic acid(PAA)films were employed as a model system,and a series of PAA films with tunable water wettability was systematically prepared by varying molecular weight and curing temperature.Using attenuated total reflectance Fourier-transform infrared spectroscopy(ATR-FTIR),the molecular configurations of surface carboxyl groups(COOH),free carboxyl(COOH_(f))and hydrogen-bonded carboxyl(COOH_(HB),were directly correlated with the polar component of surface energy(γ^(s,p)).By decomposing theγ^(s,p)values of the PAA thin films as a sum of the contributions of COOH_(f)and COOH_(H B),the intrinsic polar component of surface energy of COOH_(H B)(γ_(H B)^(s,p*))was quantified for the first time as 8.34 mN/m,significantly lower than that of COOH_(f)(γ_(f)^(s,p*)=34 mN/m).This result highlights that hydrogen bonding markedly reduces theγ^(s,p),providing a rational explanation for the relatively large water contact angle observed on PAA thin films.Furthermore,it establishes a thermodynamic basis for estimating the fraction of surface COOH_(H B)groups(f H B)from wettability measurements.Further extension of the model to carboxyl-terminated self-assembled monolayers(COOH-SAMs)revealed that surface COOH density(ΣCOOH)critically regulates wetting behavior:whenΣCOOH ranges from 4.30 to 5.25 nm^(-2),COOH groups predominantly exist in a free state and facilitate effective hydration layers,thereby promoting superhydrophilicity.Overall,this study not only establishes a unified thermodynamic framework linking surface COOH configurations to macroscopic wettability,but also validates its universality by extending it to COOH-SAMs systems,thereby providing a unified theoretical framework for the controllable design of hydrophilicity in various COOH-functionalized surfaces.展开更多
Fragment velocity distribution is an important parameter affecting the terminal effects of warheads.The rarefaction wave,end cap,and its confinement state can significantly affect the fragmentation of the cylindrical ...Fragment velocity distribution is an important parameter affecting the terminal effects of warheads.The rarefaction wave,end cap,and its confinement state can significantly affect the fragmentation of the cylindrical charge casing.Most of the existing studies have performed experiments and simulations considering the rarefaction wave and unfixed end caps;research on fixed end caps and sufficient theoretical explanations are limited.In this work,the effects of rarefaction waves,end caps,and their fixed states,on the fragment velocity distribution,were studied via experimentation and simulation,and reasonable theoretical explanations were provided.The results show that the rarefaction wave and end caps affect the fragment velocity by changing the pressure states of the detonation products.At the initiation end,the fragment velocities of casings with unfixed initiation ends are 33.3%(300 m/s)greater than that of casings without end caps,because of the weakening of the attenuation effect of the rarefaction wave.The fragment velocities of the casings with fixed initiation ends are 8.3%(100 m/s)greater than that of casings with unfixed initiation ends.At the non-initiation end,the fragment velocities are 24.8%(297 m/s)greater than that of a casing without end caps,and the reflecting shock wave generated by the fixed non-initiation end increases the fragment velocity by 7.3%(113 m/s),compared to the theoretical velocity.This work provides a basis for the structural design and analysis of the terminal effects of warheads.展开更多
Accurately forecasting the triple point(TP)path is essential for analyzing blast loads and assessing the destructive effectiveness of the height of burst explosion.Empirical models that describe the TP path under norm...Accurately forecasting the triple point(TP)path is essential for analyzing blast loads and assessing the destructive effectiveness of the height of burst explosion.Empirical models that describe the TP path under normal temperature and pressure environments are commonly employed;however,in certain configurations,such as at high-altitudes(HAs),the environment may involve low temperature and pressure conditions.The present study develops a theoretical prediction model for the TP path under reduced pressure and temperature conditions,utilizing the image bursts method,reflected polar analysis,and dimensional analysis.The model's accuracy is evaluated through numerical simulations and experimental data.Results indicate that the prediction model effectively evaluates the TP path under diminished temperature and pressure conditions,with most predictions falling within a±15%deviation.It was found that the TP height increases with altitude.As the altitude rises from 0 m to 10,000 m,the average TP height increases by 61.7%,87.9%,109.0%,and 134.3%for the scaled height of burst of 1.5 m,2.0 m,2.5 m,and 3.0 m,respectively.Moreover,the variation in TP height under HA environments closely mirrors that observed under corresponding reduced pressure conditions.In HA environments,only the effect of low-pressure conditions on the TP path needs to be considered,as the environmental lowtemperature has a minimal effect.展开更多
This feature article illustrates the potential of polarization modulation infrared reflection absorption spectroscopy(PM IRRAS)to provide molecular-level information about the structure,orientation and conformation of...This feature article illustrates the potential of polarization modulation infrared reflection absorption spectroscopy(PM IRRAS)to provide molecular-level information about the structure,orientation and conformation of constituents of thin films at electrode surfaces.PM IRRAS relies on the surface selection rules stating that the p-polarized IR beam is enhanced,while the s-polarized beam is attenuated at the metal surface.The difference between p-and s-polarized beams eliminates the background of the solvent and provides IR spectra at a single electrode potential.In contrast,two other popular in situ IR spectroscopic techniques,namely,subtractively normalized interfacial Fourier transform infrared spectroscopy(SNIFTIRS)and surface-enhanced infrared reflection absorption spectroscopy(SEIRAS),provide potential difference spectra to remove the signal from the bulk solution.In this feature article,we provide a brief tutorial on how to run the PM IRRAS experiment and describe the methods used for background elimination first.The application of the PM IRRAS in the biomimetic research is then illustrated by three examples:construction of a tethered bilayer,reconstitution of colicin into a phospholipid bilayer and determination of the orientation of nucleolipids in a monolayer assembled at a gold electrode surface.Finally,the structural changes of graphene oxide during its electrochemical reduction are described to highlight the promising application of PM IRRAS in materials science.展开更多
Objective:Verrucous epidermal nevus(VEN),seborrheic keratosis(SK),verruca plana(VP),verruca vulgaris(VV),and nevus sebaceous(NS)are common verrucous proliferative skin diseases with similar clinical appearances,often ...Objective:Verrucous epidermal nevus(VEN),seborrheic keratosis(SK),verruca plana(VP),verruca vulgaris(VV),and nevus sebaceous(NS)are common verrucous proliferative skin diseases with similar clinical appearances,often posing diagnostic challenges.Dermoscopy and reflectance confocal microscopy(RCM)can aid in their differentiation,yet their specific features under these tools have not been systematically described.This study aims to summarize and analyze the dermoscopic and RCM features of VEN,SK,VP,VV,and NS.Methods:A total of 121 patients with histopathologically confirmed verrucous proliferative skin diseases were enrolled.Dermoscopy and RCM imaging was used to observe and analyze the microscopic features of these conditions.Results:Under dermoscopy,the 5 diseases displayed distinct characteristics:VEN typically showed gyriform structures;SK was characterized by gyriform structures,comedo-like openings,and milia-like cysts;VP and VV featured dotted vessels and frogspawn-like structures;NS presented as brownish-yellow globules.RCM revealed shared features such as hyperkeratosis and acanthosis across all 5 diseases.Specific features included gyriform structures and elongated rete ridges in VEN;pseudocysts and gyriform structures in SK;evenly distributed ring-like structures in VP;vacuolated cells and papillomatous proliferation in VV;and frogspawn-like structures in NS.Conclusion:These 5 verrucous proliferative skin conditions exhibit distinguishable features under both dermoscopy and RCM.The combination of these 2 noninvasive imaging modalities holds significant clinical value for the differential diagnosis of verrucous proliferative skin diseases.展开更多
Doping perylene diimide(PDI)into a polymer matrix is a simple strategy to prepare near-infrared(NIR)reflective materials,but the mechanical properties and NIR reflectance properties are significantly compromised due t...Doping perylene diimide(PDI)into a polymer matrix is a simple strategy to prepare near-infrared(NIR)reflective materials,but the mechanical properties and NIR reflectance properties are significantly compromised due to macro-phase separation.In this study,a novel polymer(denoted as PU-PDI)with intrinsic NIR reflective proper⁃ties was synthesized by covalent incorporation of PDI units into polyurethane chains.Its photophysical characteris⁃tics,mechanical property and NIR reflectance property are investigated in detail.The results show that covalent in⁃corporation reduces the severe aggregation of PDI units,thereby endows PU-PDI with excellent mechanical property.The elongation at break of PU-PDI can reach more than 700%,and the breaking strength is 34.11 MPa.Moreover,compared to the blending system,PU-PDI possesses enhanced NIR reflection ability due to the better dispersion of PDI units.展开更多
遥感卫星的多光谱数据应用于找矿已取得显著成效,2004年7月中国卫星地面站开始提供ASTER(Advanced Space-borne Thermal Emission and Reflection Radiometer,高级星载热发射反照辐射计)数据,因涵盖波长范围宽[VNIR(Visible and Near In...遥感卫星的多光谱数据应用于找矿已取得显著成效,2004年7月中国卫星地面站开始提供ASTER(Advanced Space-borne Thermal Emission and Reflection Radiometer,高级星载热发射反照辐射计)数据,因涵盖波长范围宽[VNIR(Visible and Near Infra-red)、SWIR(Short wave-length Infra-red)、TIR(Thermal Infra-red)]、波段多(14个波段)、性价比合理等因素,ASTER数据的研究迅速发展。长久以来,对覆盖区进行蚀变遥感异常信息提取一直是遥感找矿的关注点之一。笔者等利用ASTER数据对浅覆盖区——包古图斑岩铜矿的Ⅱ号、Ⅴ号斑岩体进行蚀变遥感异常提取,提取的蚀变异常与野外地质情况吻合性好。分别提取了光谱特征谱带差异明显的2组蚀变矿物的异常信息:第一组是蒙脱石、埃洛石、伊利石与绢云母;第二组是方解石、黑云母与绿泥石。提出了需要进一步工作的异常靶区。展开更多
基金Project(NRF-2010-0024155) supported by the National Research Foundation of Korea
文摘This research was conducted to study the performances of the heat and multilayer reflection insulators used for buildings in South Korea to realize eco-friendly, low-energy-consumption, green construction, and to contribute to energy consumption reduction in buildings and to the nation＇s greenhouse gas emission reduction policy （targeting 30% reduction compared to BAUCousiness as usual） by 2020）. The heat insulation performance test is about the temperatures on surfaces of test piece. The high air temperature and the low air temperature were measured to determine the overall heat transfer coefficient and thermal conductivity. The conclusions are drawn that the heat transmission coefficients for each type of existing reflection insulator are： A-1 （0.045 W/（m-K））, A-2 （0.031 W/（m.K））, A-3 （0.042 W/（m.K））, A-4 （0.078 W/（m.K））, and the average heat conductivity is 0.049 W/（m-K）; The heat conductivity for each type of Styrofoam insulator are 0.030 W/（m.K） for B-l, 0.032 W/（m-K） for B-2, 0.037 W/（m＇K） for B-3, 0.037 W/（m.K） for B-4, and the average heat conductivity is 0.035 W/（m＇K） regardless of the thickness of the insulator; The heat conductivity values of the multilayer reflection insulators are converted based on the thickness and type C-1 （0.020 W/（m.K））, C-2 （0.018 W/（m.K））, C-3 （0.016 W/（m.K））, and C-4 （0.012 W/（m.K））; The multilayer reflection insulator keeps the indoor-side surface temperature high （during winter） or low （in summer）, enhances the comfort of the building occupants, and conducts heating and moisture resistance to prevent dew condensation on the glass-outer-wall surface.
文摘The collision between the Indian and Asian plates uplifted the Himalayan-Tibetan Plateau,thickening and expanding the crust.It is a scientific mystery of global concern as how the two continents collide and how the continent-continent collision deforms the continent.Deep seismic reflection profile detection is one of the most effective ways to unlock this scientific mystery.For more than 20 years using this technology,we have detected fine structures of the thick crust of the Tibetan plateau after overcoming technical bottlenecks to access the lower crust and Moho thus revealing the continental collision processes.This paper systematically summarizes the deep behaviors of the India-Asia collision and subduction beneath the Tibetan Plateau,from south to north,east to west and further into the hinterland of the plateau.The Indian crust undergoes underthrusting beneath the Himalayan orogenic belt on the southern margin of the plateau.Meanwhile,the lithosphere of the Alxa block in the Asian plate subducts southward beneath the Qilian Mountain in the north of the plateau,driving the northward overthrusting of the Qilian crust.Additionally,the Tarim and West Kunlun blocks undergo face-to-face collision in the northwestern margin of the plateau.In the easternmost part of the plateau,the Longriba fault,instead of the Longmen Shan fault zone,marks the western margin of the Yangtze block.It is also seismically evidenced that the Moho geometry in the plateaus hinterland appears thin and flat,indicating lithospheric collapse and extrusion.Multiple deep reflection profiles revealed the collisional behavior under the Yalung-Zangbo suture zone and longitudinal variation in subducting geometry of the Indian crust from west to the east.In the middle of the suture zone,it shows a decoupling between the upper and lower crusts of the Indian plate,where the upper crust undergoes a northward overthrusting while the lower one experiences a northward underthrusting.It is also seismically evidenced a down-and southward crustal duplexing of the subducting Indian crust thickening the northern Himalayas,leaving over a thinning subducting lower crust of the Indian slab.The subduction front of the Indian crust collides with the lower crust of the Asian plate at the mantle depth.A near-vertical collision boundary is seen between the Gangdese batholith and the Tethyan Himalayas,where the Gangdese batholith shows almost transparent weak reflections in the lower crust with localized bright spot reflection that indicates partial melting.Additionally,the near-flat Moho geometry implies an extensional tectonic environment of the southern margin of the Asian plate.
文摘Altun fault is regarded as a large\|scale sinistral strike\|slip fault, it is composed of several faults with the different character, and there is a special geological structure in the fault belt, and they constitute the northwestern margin fault belt of the Qinghai\|Tibetan plateau. In order to investigate the deep crust structure in the Altun region, layers which Tarim lithosphere subducted beneath the Qinghai\|Tibetan plateau, the forward structure of the subduction plate and the scale of the plate subduction, a deep seismic reflection profile was designed. Data collection work of the deep seismic reflection profile across Altun fault was completed during 24/8/1999 to 25/9/1999. The profile locates in Qiemo county, Xinjiang Uygur Autonomous Region, the southern end of the profile stretches into Altun Mountains, the northern end locates in the Tarim desert margin. The profile is nearly SN trending and crosses the main Altun fault. The profile totally is 145km long, time record is 30 seconds, the smallest explosive amount is 72～100kg, the biggest explosive amount reaches 200～300kg, the explosive distance is 800m, and detectors are laid at a 50m distance.
基金the National Natural Science Foundation of China(61901493,61901492,61801485)the Natural Science Foundation of Hunan Province(2020JJ5676).
文摘The electric-controlled metasurface antenna array(ECMSAA)with ultra-wideband frequency reconfigurable reflection suppression is proposed and realized.Firstly,an electriccontrolled metasurface with ultra-wideband frequency reconfigurable in-phase reflection characteristics is designed.The element of the ECMSAA is constructed by loading the single electric-controlled metasurface unit on the conventional patch antenna element.The radiation properties of the conventional patch antenna and the reflection performance of electric-controlled metasurface are maintained when the antenna and the metasurface are integrated.Thus,the ECMSAA elements have excellent radiation properties and ultra-wideband frequency reconfigurable in-phase reflection characteristics simultaneously.To take a further step,a 6×10 ECMSAA is realized based on the designed metasurface antenna element.Simulated and measured results prove that the reflection of the ECMSAA is dynamically suppressed in the P and L bands.Meanwhile,high-gain and multi-polarization radiation properties of the ECMSAA are achieved.This design method not only realizes the frequency reconfigurable reflection suppression of the antenna array in the ultra-wide frequency band but also provides a way to develop an intelligent low-scattering antenna.
文摘The current work is an extension of the nonlocal elasticity theory to fractional order thermo-elasticity in semiconducting nanostructure medium with voids.The analysis is made on the reflection phenomena in context of three-phase-lag thermo-elastic model.It is observed that,four-coupled longitudinal waves and an independent shear vertical wave exist in the medium which is dispersive in nature.It is seen that longitudinal waves are damped,and shear wave is un-damped when angular frequency is less than the cut-off frequency.The voids,thermal and non-local parameter affect the dilatational waves whereas shear wave is only depending upon non-local parameter.It is found that reflection coefficients are affected by nonlocal and fractional order parameters.Reflection coefficients are calculated analytically and computed numerically for a material,silicon and discussed graphically in details.The results for local(classical)theory are obtained as a special case.The study may be useful in semiconductor nanostructure,geology and seismology in addition to semiconductor nanostructure devices.
基金financially supported by A*STAR, SERC 2014 Public Sector Research Funding (PSF) (Grant: SERC Project 1421200080)973 Program of China (2013CBA01700)+1 种基金Chinese Nature Science Grant (61675207)Mr.Li Yang acknowledges the support from China Scholarship Council (CSC)
文摘Reflection engineering plays an important role in optics.For conventional approaches,the reflection tuning is quite challenging in a loss-free component.Therefore,a simple approach to tune the reflection is highly desired in plenty of applications.In this paper,we propose a new design of metasurface with just one single layer dielectric structure to tune the reflection of an interface by destructive interference in a subwavelength scale.By arranging the orientation of nano-antennas,the reflectivity tuning from 20%to 90%can be achieved at the wavelength of 1550 nm.Moreover,such reflectivity tuning of the designed metasurface works at the tunable wavelength from1500 nm to 1600 nm.This ultra-thin solution can achieve similar performance as the traditional bulky components without diffraction orders,while the design and fabrication are much simple and flexible.The ultra-thin and tunable properties indicate the great potentials of this method to be applied in laser fabrication,optical communication and optical integration.
基金supported by the National Natural Science Foundation of China(62075239,61302145).
文摘Specific to the reflected light problem on the surface of transparent body,the polarization characteristics of the reflection region are analyzed,and a polarization characterization model combining the reflection and transmission effects is established.On the basis of the polarization characteristic analysis,the minimum value of normalized cross-correlation(NCC)coefficient between transmission and reflection images is solved through the gradient descent method,and their polarization degrees under the minimum correlation are acquired.According to the distribution relations of the transmitted and reflected lights in perpendicular and parallel directions,reflection separation is realized via the polarized orthogonality difference algorithm based on the degree of reflection polarization and the degree of transmission polarization.
基金supported by the National Natural Science Foundation of China(61901493,61901492)the Natural Science Foundation of Hunan Province(2020JJ5676)the Science and Technology Innovation Program of Hunan Province(2020RC2048).
文摘The electromagnetic surface antenna array(EMSAA)has been proposed for obtaining reflection suppression and excellent radiation simultaneously.The antenna with rectangular radiation patch is used to design anisotropic electromagnetic surface.Preternatural reflection characteristics of the element antenna can be tailored depending on the incident polarizations.EMSAA can be constructed by using single structured element antenna with 90° rotation and orthometric arrangement.This orthometric arrangement of EMSAA is helpful to achieve reflection suppression and excellent radiation.The simulated results show that the reflection of EMSAA is suppressed from 5.0 GHz to 8.0 GHz with peak reduction of 12.3 dB.The linear-and circular-polarized radiation properties of EMSAA are obtained and the maximum gain is 14.3 dBi.The measured results are consistent with the simulation results.The results demonstrate that the reflection suppression and excellent radiation are achieved simultaneously.Such design of EMSAA will open the path for integrating antenna fields and electromagnetic surface(EMS)fields.
文摘The influence of the most important parameters on the service life of reinforced asphalt overlay with geogrid materials in bending mode was examined by employing the Taguchi method and analysis of variance techniques. The objectives of this experiment was to investigate the effects of grid stiffness, tensile strength, coating type, amount of tack coat, overlay thickness, crack width and stiffnesses of asphalt overlay and existing asphalt concrete on propagation of the reflection cracking. Results indicate that the stiffnesses of cracked layer and overlay are the main significant factors that can directly improve the service life of an overlay against the reflection cracking. Generally, glass grid is more effective in reinforced overlay than polyester grid. Effect of crack width of the existing layer is significant when its magnitude increases from 6 to 9 mm.
基金Project(2009AA05Z215) supported by the National High-Tech Research and Development Program of China
文摘The radiative properties of three different materials surfaces with one-dimensional microscale random roughness were obtained with the finite difference time domain method(FDTD) and near-to-far-field transformation.The surface height conforms to the Gaussian probability density function distribution.Various computational modeling issues that affect the accuracy of the predicted properties were discussed.The results show that,for perfect electric conductor(PEC) surfaces,as the surface roughness increases,the magnitude of the spike reduces and eventually the spike disappears,and also as the ratio of root mean square roughness to the surface correlation distance increases,the retroreflection becomes evident.The predicted values of FDTD solutions are in good agreement with the ray tracing and integral equation solutions.The overall trend of bidirectional reflection distribution function(BRDF) of PEC surfaces and silicon surfaces is the same,but the silicon's is much less than the former's.The BRDF difference from two polarization modes for the gold surfaces is little for smaller wavelength,but it is much larger for the longer wavelength and the FDTD simulation results agree well with the measured data.In terms of PEC surfaces,as the incident angle increases,the reflectivity becomes more specular.
基金supported by the National Natural Science Foundation of China(61771367)the Science and Technology on Communication Networks Laboratory(6142104190204).
文摘It is always a challenging issue for radar systems to estimate the height of a low-angle target in the multipath propagation environment.The highly deterministic maximum likelihood estimator has a high accuracy,but the errors of the ground reflection coefficient and the reflecting surface height have serious influence on the method.In this paper,a robust es-timation method with less computation burden is proposed based on the compound reflection coefficient multipath model for low-angle targets.The compound reflection coefficient is es-timated from the received data of the array and then a one-di-mension generalized steering vector is constructed to estimate the target height.The algorithm is robust to the reflecting sur-face height error and the ground reflection coefficient error.Fi-nally,the experiment and simulation results demonstrate the validity of the proposed method.
文摘Being the core of the Songpan-Ganze block,Zoig(?)Basin is a favorable zone of oil and gas exploration.And it not only is the important deposition area of the northern Songpan-Garze in the Middle-Late Triassic,but also impacts on the formation and evolution of the structural belt.
文摘In this study,polyacrylic acid(PAA)films were employed as a model system,and a series of PAA films with tunable water wettability was systematically prepared by varying molecular weight and curing temperature.Using attenuated total reflectance Fourier-transform infrared spectroscopy(ATR-FTIR),the molecular configurations of surface carboxyl groups(COOH),free carboxyl(COOH_(f))and hydrogen-bonded carboxyl(COOH_(HB),were directly correlated with the polar component of surface energy(γ^(s,p)).By decomposing theγ^(s,p)values of the PAA thin films as a sum of the contributions of COOH_(f)and COOH_(H B),the intrinsic polar component of surface energy of COOH_(H B)(γ_(H B)^(s,p*))was quantified for the first time as 8.34 mN/m,significantly lower than that of COOH_(f)(γ_(f)^(s,p*)=34 mN/m).This result highlights that hydrogen bonding markedly reduces theγ^(s,p),providing a rational explanation for the relatively large water contact angle observed on PAA thin films.Furthermore,it establishes a thermodynamic basis for estimating the fraction of surface COOH_(H B)groups(f H B)from wettability measurements.Further extension of the model to carboxyl-terminated self-assembled monolayers(COOH-SAMs)revealed that surface COOH density(ΣCOOH)critically regulates wetting behavior:whenΣCOOH ranges from 4.30 to 5.25 nm^(-2),COOH groups predominantly exist in a free state and facilitate effective hydration layers,thereby promoting superhydrophilicity.Overall,this study not only establishes a unified thermodynamic framework linking surface COOH configurations to macroscopic wettability,but also validates its universality by extending it to COOH-SAMs systems,thereby providing a unified theoretical framework for the controllable design of hydrophilicity in various COOH-functionalized surfaces.
基金the support of the Youth Scientific Research Projects of the Basic Research Program of Shanxi Province(Grant Nos.202303021222111,202303021222113)the China Postdoctoral Science Foundation(Grant No.2025M770001).
文摘Fragment velocity distribution is an important parameter affecting the terminal effects of warheads.The rarefaction wave,end cap,and its confinement state can significantly affect the fragmentation of the cylindrical charge casing.Most of the existing studies have performed experiments and simulations considering the rarefaction wave and unfixed end caps;research on fixed end caps and sufficient theoretical explanations are limited.In this work,the effects of rarefaction waves,end caps,and their fixed states,on the fragment velocity distribution,were studied via experimentation and simulation,and reasonable theoretical explanations were provided.The results show that the rarefaction wave and end caps affect the fragment velocity by changing the pressure states of the detonation products.At the initiation end,the fragment velocities of casings with unfixed initiation ends are 33.3%(300 m/s)greater than that of casings without end caps,because of the weakening of the attenuation effect of the rarefaction wave.The fragment velocities of the casings with fixed initiation ends are 8.3%(100 m/s)greater than that of casings with unfixed initiation ends.At the non-initiation end,the fragment velocities are 24.8%(297 m/s)greater than that of a casing without end caps,and the reflecting shock wave generated by the fixed non-initiation end increases the fragment velocity by 7.3%(113 m/s),compared to the theoretical velocity.This work provides a basis for the structural design and analysis of the terminal effects of warheads.
基金funding from Anhui Engineering Laboratory of Explosive Materials and Technology Foundation(No.AHBP2022B-04)Natural Science Research Project of Anhui Educational Committee(No.2023AH051221)+1 种基金Anhui Provincial Natural Science Foundation(No.2208085QA26)Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology for the project related to this work.
文摘Accurately forecasting the triple point(TP)path is essential for analyzing blast loads and assessing the destructive effectiveness of the height of burst explosion.Empirical models that describe the TP path under normal temperature and pressure environments are commonly employed;however,in certain configurations,such as at high-altitudes(HAs),the environment may involve low temperature and pressure conditions.The present study develops a theoretical prediction model for the TP path under reduced pressure and temperature conditions,utilizing the image bursts method,reflected polar analysis,and dimensional analysis.The model's accuracy is evaluated through numerical simulations and experimental data.Results indicate that the prediction model effectively evaluates the TP path under diminished temperature and pressure conditions,with most predictions falling within a±15%deviation.It was found that the TP height increases with altitude.As the altitude rises from 0 m to 10,000 m,the average TP height increases by 61.7%,87.9%,109.0%,and 134.3%for the scaled height of burst of 1.5 m,2.0 m,2.5 m,and 3.0 m,respectively.Moreover,the variation in TP height under HA environments closely mirrors that observed under corresponding reduced pressure conditions.In HA environments,only the effect of low-pressure conditions on the TP path needs to be considered,as the environmental lowtemperature has a minimal effect.
基金This research was funded by Discovery Grants from the Natural Sciences and Engineering Research Council of Canada(JL:RGPIN-2022-03958AC:RGPIN-2022-04238).
文摘This feature article illustrates the potential of polarization modulation infrared reflection absorption spectroscopy(PM IRRAS)to provide molecular-level information about the structure,orientation and conformation of constituents of thin films at electrode surfaces.PM IRRAS relies on the surface selection rules stating that the p-polarized IR beam is enhanced,while the s-polarized beam is attenuated at the metal surface.The difference between p-and s-polarized beams eliminates the background of the solvent and provides IR spectra at a single electrode potential.In contrast,two other popular in situ IR spectroscopic techniques,namely,subtractively normalized interfacial Fourier transform infrared spectroscopy(SNIFTIRS)and surface-enhanced infrared reflection absorption spectroscopy(SEIRAS),provide potential difference spectra to remove the signal from the bulk solution.In this feature article,we provide a brief tutorial on how to run the PM IRRAS experiment and describe the methods used for background elimination first.The application of the PM IRRAS in the biomimetic research is then illustrated by three examples:construction of a tethered bilayer,reconstitution of colicin into a phospholipid bilayer and determination of the orientation of nucleolipids in a monolayer assembled at a gold electrode surface.Finally,the structural changes of graphene oxide during its electrochemical reduction are described to highlight the promising application of PM IRRAS in materials science.
基金supported by the Project of Health Committee of Hunan Province(D202304128868),China.
文摘Objective:Verrucous epidermal nevus(VEN),seborrheic keratosis(SK),verruca plana(VP),verruca vulgaris(VV),and nevus sebaceous(NS)are common verrucous proliferative skin diseases with similar clinical appearances,often posing diagnostic challenges.Dermoscopy and reflectance confocal microscopy(RCM)can aid in their differentiation,yet their specific features under these tools have not been systematically described.This study aims to summarize and analyze the dermoscopic and RCM features of VEN,SK,VP,VV,and NS.Methods:A total of 121 patients with histopathologically confirmed verrucous proliferative skin diseases were enrolled.Dermoscopy and RCM imaging was used to observe and analyze the microscopic features of these conditions.Results:Under dermoscopy,the 5 diseases displayed distinct characteristics:VEN typically showed gyriform structures;SK was characterized by gyriform structures,comedo-like openings,and milia-like cysts;VP and VV featured dotted vessels and frogspawn-like structures;NS presented as brownish-yellow globules.RCM revealed shared features such as hyperkeratosis and acanthosis across all 5 diseases.Specific features included gyriform structures and elongated rete ridges in VEN;pseudocysts and gyriform structures in SK;evenly distributed ring-like structures in VP;vacuolated cells and papillomatous proliferation in VV;and frogspawn-like structures in NS.Conclusion:These 5 verrucous proliferative skin conditions exhibit distinguishable features under both dermoscopy and RCM.The combination of these 2 noninvasive imaging modalities holds significant clinical value for the differential diagnosis of verrucous proliferative skin diseases.
文摘Doping perylene diimide(PDI)into a polymer matrix is a simple strategy to prepare near-infrared(NIR)reflective materials,but the mechanical properties and NIR reflectance properties are significantly compromised due to macro-phase separation.In this study,a novel polymer(denoted as PU-PDI)with intrinsic NIR reflective proper⁃ties was synthesized by covalent incorporation of PDI units into polyurethane chains.Its photophysical characteris⁃tics,mechanical property and NIR reflectance property are investigated in detail.The results show that covalent in⁃corporation reduces the severe aggregation of PDI units,thereby endows PU-PDI with excellent mechanical property.The elongation at break of PU-PDI can reach more than 700%,and the breaking strength is 34.11 MPa.Moreover,compared to the blending system,PU-PDI possesses enhanced NIR reflection ability due to the better dispersion of PDI units.
文摘遥感卫星的多光谱数据应用于找矿已取得显著成效,2004年7月中国卫星地面站开始提供ASTER(Advanced Space-borne Thermal Emission and Reflection Radiometer,高级星载热发射反照辐射计)数据,因涵盖波长范围宽[VNIR(Visible and Near Infra-red)、SWIR(Short wave-length Infra-red)、TIR(Thermal Infra-red)]、波段多(14个波段)、性价比合理等因素,ASTER数据的研究迅速发展。长久以来,对覆盖区进行蚀变遥感异常信息提取一直是遥感找矿的关注点之一。笔者等利用ASTER数据对浅覆盖区——包古图斑岩铜矿的Ⅱ号、Ⅴ号斑岩体进行蚀变遥感异常提取,提取的蚀变异常与野外地质情况吻合性好。分别提取了光谱特征谱带差异明显的2组蚀变矿物的异常信息:第一组是蒙脱石、埃洛石、伊利石与绢云母;第二组是方解石、黑云母与绿泥石。提出了需要进一步工作的异常靶区。
