In this paper, the outdoor microcellular radio propagation characteristics at 3.5 GHz are simulated and analyzed by the method of SBR/Image (Shooting and bouncing ray tracing/Image). A good agreement is achieved betwe...In this paper, the outdoor microcellular radio propagation characteristics at 3.5 GHz are simulated and analyzed by the method of SBR/Image (Shooting and bouncing ray tracing/Image). A good agreement is achieved between the results simulated and the results given in published literature. So the correctness of the method has been validated. Some simulated propagation parameters of LOS (Line-of-sight) and NLOS (None-line-of-sight) have been compared. The analysis of the above results provides the foundation for the coverage of outdoor microcellular systems.展开更多
We demonstrated an optical fiber frequency comb stabilized to an acetylene-filled photonic microcell.The short-term instability of the comb at 1 s gate time was 1.66×10^(-12)for a 4.2-h measurement in a laborator...We demonstrated an optical fiber frequency comb stabilized to an acetylene-filled photonic microcell.The short-term instability of the comb at 1 s gate time was 1.66×10^(-12)for a 4.2-h measurement in a laboratory environment with air conditioning.This is the best short-term stability reported for a compact fiber comb stabilized to an acetylene-filled photonic microcell at telecom wavelengths.It is particularly significant in the development of compact fiber combs with target instability of 10^(-13).Such a device has the potential to serve as an alternative to GPS in areas lacking signal coverage,including remote locations,regions with adverse weather conditions,and military intelligence areas.展开更多
An array electrode technique was developed as a novel electrochemical method for studying the interaction between macrocell and microcell in the early corrosion process of reinforcing steel in cement mortar.The corros...An array electrode technique was developed as a novel electrochemical method for studying the interaction between macrocell and microcell in the early corrosion process of reinforcing steel in cement mortar.The corrosion potential and galvanic current of macrocell corrosion of the reinforcing steel in cement mortar were imaged by the array electrode technique during the corrosion initiation and propagation.It was certified that the corrosion macrocell current is closely related with the difference of corrosion potential between the anodic and cathodic areas.The corrosion macrocell and microcell always exist during the corrosion process.The interaction of corrosion macrocell and corrosion microcell of steel in concrete was directly sensed by the array electrode for the first time,and was discussed in terms of corrosion electrochemistry.展开更多
Oncogenes have been identified using DNA-mediated transfection, but the size of the transferable and unrearranged DNA, gene rearrangement and amplification which occur during the transfection process limit the use of ...Oncogenes have been identified using DNA-mediated transfection, but the size of the transferable and unrearranged DNA, gene rearrangement and amplification which occur during the transfection process limit the use of the techniques. We have evaluated microcell-mediated gene transfer techniques for the transfer and analysis of dominant oncogenes. MNNG-HOS, a transformed human cell line which contained the met oncogene mapping to human chromosome 7 was infected with retroviruses carrying drug resistance markers and used to optimize microcell preparation and transfer. Stable and drug-resistant hybrids containing single human chromosomes as well as the foci of the transformed cells containing the activated met oncogene and intact hitman chromosomes were obtained. Hybridization analysis with probes (i.e. collA2, pJ3.11) mapping up to 1 Mb away from met shows that the cells from the individual focr contain different amounts of apparently unrearranged human DNA associated with the oncogene, and the microcell-generated transformants retain more distal markers than those observed in either DNA- or chromosome-mediated transfers. In conjunction with other techniques, microcell fusion should be useful for gene mapping as well as the study of gene function and expression in cell transformation and malignancy.展开更多
Three-dimensional(3D)printed re-entrant micropillars have demonstrated high static contact angles for an unprecedented variety of liquids,but have yet to achieve this with low contact angle hysteresis and excellent ab...Three-dimensional(3D)printed re-entrant micropillars have demonstrated high static contact angles for an unprecedented variety of liquids,but have yet to achieve this with low contact angle hysteresis and excellent abrasion resistance.We report on the demonstration of 3D printed microcell/nanoparticle structures that exhibit high static contact angle,low contact angle hysteresis,and high mechanical durability.Micropillars and microcells both exhibit high static contact angles with water and ethylene glycol(EG),but suffer from high contact angle hysteresis,indicative of rose petal wetting.Our modeling results indicate that micropillars are able to achieve higher static contact angle and breakthrough pressure simultaneously compared with microcells.However,simulations also indicate that micropillars have higher maximum equivalent stress at their bases,so that they are more prone to mechanical failure.We address contact angle hysteresis and mechanical durability issues by the creation of 3D printed microcell/nanoparticle arrays that demonstrate super-repellency and retain their super-repellency after 100 cycles of mechanical abrasion with a Scotch-Brite abrasive pad under a pressure of 1.2 kPa.The use of interconnected microcell structures as opposed to micropillars addresses mechanical durability issues.Low contact angle hysteresis is realized by coating 3D printed structures with low surface energy nanoparticles,which lowers the solid–liquid contact area fraction.Our results demonstrate new 3D printed structures with mechanical durability and super-repellency through the use of microcell structures integrated with fluorinated nanoparticles.展开更多
Study of damage and fracture models to analyze the fracture mechanism of eutectic composite ceramics is of considerable importance because no accurate fracture models are available for these materials. Eutectic compos...Study of damage and fracture models to analyze the fracture mechanism of eutectic composite ceramics is of considerable importance because no accurate fracture models are available for these materials. Eutectic composite ceramics are composed of microcells with random direction. We present herein a model that predicts the damage and fracture of eutectic composite ceramics based on analysis of defect stability and the damage localization band. Firstly, given the microstructure of eutectic composite ceramics, a mesodomain and a microcell model are constructed. The local stress field in the mesodomain is then analyzed based on the interaction direct derivative estimate. Secondly, the stability of a defect around particles in a microcell is analyzed, and the stress intensity factor of an annular defect under the applied stress field and the residual stress field in the particle are calculated. The stress intensity factor of a defect is controlled by the residual stress when the defect extension is small. However, it is controlled by the applied stress when the defect extension is large. Finally, a model for the damage localization band at the crack tip is constructed based on the Dugdale-Barenblatt model. The residual intensity is the important factor affecting the length of the damage localization band. When the damage variables reach their largest value, the residual in ten sity and the length of the damage localization band attain their minimum value. This work provides the theoretical basis for further study of the damage mechanics of eutectic composite ceramics and guides the engineering applications of these materials.展开更多
In this paper, firstly presented a geometrically based statistical channel model with scatterers that are with an inverted parabolic spatial distribution around mobile station (MS) within a circle wherein the base s...In this paper, firstly presented a geometrically based statistical channel model with scatterers that are with an inverted parabolic spatial distribution around mobile station (MS) within a circle wherein the base station (BS) and MS are included. This paper proposed a technique to simply derive probability density functions (PDFs) of angle of arrival (AOA), time of arrival (TOA) and Doppler spectra to characterize the outdoor macrocell and microcell environments by employing various distances between BS and MS, or different size of circular region. Employing this channel model, we analyze the impacts of a directional antenna at BS with the main-lobe width 2~z on the fading and the Doppler spectra.展开更多
文摘In this paper, the outdoor microcellular radio propagation characteristics at 3.5 GHz are simulated and analyzed by the method of SBR/Image (Shooting and bouncing ray tracing/Image). A good agreement is achieved between the results simulated and the results given in published literature. So the correctness of the method has been validated. Some simulated propagation parameters of LOS (Line-of-sight) and NLOS (None-line-of-sight) have been compared. The analysis of the above results provides the foundation for the coverage of outdoor microcellular systems.
基金supported by the Campus Science Foundation of Wuhan Institute of Technology(No.22QD01)the Open Research Fund of State Key Laboratory of Transient Optics and Photonics(No.SKLST202105)the Hubei Province Natural Science Foundation(No.2023AFB778)。
文摘We demonstrated an optical fiber frequency comb stabilized to an acetylene-filled photonic microcell.The short-term instability of the comb at 1 s gate time was 1.66×10^(-12)for a 4.2-h measurement in a laboratory environment with air conditioning.This is the best short-term stability reported for a compact fiber comb stabilized to an acetylene-filled photonic microcell at telecom wavelengths.It is particularly significant in the development of compact fiber combs with target instability of 10^(-13).Such a device has the potential to serve as an alternative to GPS in areas lacking signal coverage,including remote locations,regions with adverse weather conditions,and military intelligence areas.
基金supported by the National Natural Science Foundation of China (Grant No.50731004)the Technology Support Programs of China (Grant No.2007BAB27B04)
文摘An array electrode technique was developed as a novel electrochemical method for studying the interaction between macrocell and microcell in the early corrosion process of reinforcing steel in cement mortar.The corrosion potential and galvanic current of macrocell corrosion of the reinforcing steel in cement mortar were imaged by the array electrode technique during the corrosion initiation and propagation.It was certified that the corrosion macrocell current is closely related with the difference of corrosion potential between the anodic and cathodic areas.The corrosion macrocell and microcell always exist during the corrosion process.The interaction of corrosion macrocell and corrosion microcell of steel in concrete was directly sensed by the array electrode for the first time,and was discussed in terms of corrosion electrochemistry.
文摘Oncogenes have been identified using DNA-mediated transfection, but the size of the transferable and unrearranged DNA, gene rearrangement and amplification which occur during the transfection process limit the use of the techniques. We have evaluated microcell-mediated gene transfer techniques for the transfer and analysis of dominant oncogenes. MNNG-HOS, a transformed human cell line which contained the met oncogene mapping to human chromosome 7 was infected with retroviruses carrying drug resistance markers and used to optimize microcell preparation and transfer. Stable and drug-resistant hybrids containing single human chromosomes as well as the foci of the transformed cells containing the activated met oncogene and intact hitman chromosomes were obtained. Hybridization analysis with probes (i.e. collA2, pJ3.11) mapping up to 1 Mb away from met shows that the cells from the individual focr contain different amounts of apparently unrearranged human DNA associated with the oncogene, and the microcell-generated transformants retain more distal markers than those observed in either DNA- or chromosome-mediated transfers. In conjunction with other techniques, microcell fusion should be useful for gene mapping as well as the study of gene function and expression in cell transformation and malignancy.
基金supported in part by the National Science Foundation(No.ECCS 1552712).
文摘Three-dimensional(3D)printed re-entrant micropillars have demonstrated high static contact angles for an unprecedented variety of liquids,but have yet to achieve this with low contact angle hysteresis and excellent abrasion resistance.We report on the demonstration of 3D printed microcell/nanoparticle structures that exhibit high static contact angle,low contact angle hysteresis,and high mechanical durability.Micropillars and microcells both exhibit high static contact angles with water and ethylene glycol(EG),but suffer from high contact angle hysteresis,indicative of rose petal wetting.Our modeling results indicate that micropillars are able to achieve higher static contact angle and breakthrough pressure simultaneously compared with microcells.However,simulations also indicate that micropillars have higher maximum equivalent stress at their bases,so that they are more prone to mechanical failure.We address contact angle hysteresis and mechanical durability issues by the creation of 3D printed microcell/nanoparticle arrays that demonstrate super-repellency and retain their super-repellency after 100 cycles of mechanical abrasion with a Scotch-Brite abrasive pad under a pressure of 1.2 kPa.The use of interconnected microcell structures as opposed to micropillars addresses mechanical durability issues.Low contact angle hysteresis is realized by coating 3D printed structures with low surface energy nanoparticles,which lowers the solid–liquid contact area fraction.Our results demonstrate new 3D printed structures with mechanical durability and super-repellency through the use of microcell structures integrated with fluorinated nanoparticles.
基金the National Natural Science Foundation of China(Grant 11272355).
文摘Study of damage and fracture models to analyze the fracture mechanism of eutectic composite ceramics is of considerable importance because no accurate fracture models are available for these materials. Eutectic composite ceramics are composed of microcells with random direction. We present herein a model that predicts the damage and fracture of eutectic composite ceramics based on analysis of defect stability and the damage localization band. Firstly, given the microstructure of eutectic composite ceramics, a mesodomain and a microcell model are constructed. The local stress field in the mesodomain is then analyzed based on the interaction direct derivative estimate. Secondly, the stability of a defect around particles in a microcell is analyzed, and the stress intensity factor of an annular defect under the applied stress field and the residual stress field in the particle are calculated. The stress intensity factor of a defect is controlled by the residual stress when the defect extension is small. However, it is controlled by the applied stress when the defect extension is large. Finally, a model for the damage localization band at the crack tip is constructed based on the Dugdale-Barenblatt model. The residual intensity is the important factor affecting the length of the damage localization band. When the damage variables reach their largest value, the residual in ten sity and the length of the damage localization band attain their minimum value. This work provides the theoretical basis for further study of the damage mechanics of eutectic composite ceramics and guides the engineering applications of these materials.
基金supported by the National Natural Science Foundation of China(61072137)the Scientific & Technological Support Project (Industry) of Jiangsu Province(BE2011298)the National overseas study support Foundation Item(20071108)
文摘In this paper, firstly presented a geometrically based statistical channel model with scatterers that are with an inverted parabolic spatial distribution around mobile station (MS) within a circle wherein the base station (BS) and MS are included. This paper proposed a technique to simply derive probability density functions (PDFs) of angle of arrival (AOA), time of arrival (TOA) and Doppler spectra to characterize the outdoor macrocell and microcell environments by employing various distances between BS and MS, or different size of circular region. Employing this channel model, we analyze the impacts of a directional antenna at BS with the main-lobe width 2~z on the fading and the Doppler spectra.