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Silk damping in scalar-induced gravitational waves: a novel probe for new physics

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 79-85页

作者： Yan-Heng Yu sai wang Theoretical Physics Division Institute of High Energy Physics Chinese Academy of Sciences School of Physics University of Chinese Academy of Sciences

Silk damping is well known in the study of cosmic microwave background（CMB） and accounts for suppression of the angular power spectrum of CMB on large angular multipoles. In this article, we study the effect of Silk damping on the scalar-induced gravitational waves（SIGWs）. Resulting from the dissipation of cosmic fluid, the Silk damping notably suppresses the energydensity spectrum of SIGWs on scales comparable to a diffusion scale at the decoupling time of weakly-interacting particles. The effect offers a novel observable for probing the underlying particle interaction, especially for those mediated by heavy gauge bosons beyond the standard model of particles. We anticipate that pulsar timing arrays are sensitive to gauge bosons with mass ～10～3-10～4 GeV, while space-and ground-based interferometers to those with mass ～10～7-1012GeV, leading to essential complements to on-going and future experiments of high-energy physics.

关键词： scalar-induced gravitational waves Silk damping new physics

Measuring the anisotropies in astrophysical and cosmological gravitational-wave backgrounds with Taiji and LISA networks

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Science China(Physics,Mechanics & Astronomy) 2024年第12期67卷 61-69页

作者： Zhi-Chao Zhao sai wang Department of Applied Physics College of ScienceChina Agricultural UniversityBeijing 100083China Theoretical Physics Division Institute of High Energy PhysicsChinese Academy of SciencesBeijing 00049China

We investigate the capabilities of space-based gravitational-wave detector networks,specifically Taiji and LISA,to measure the anisotropies in stochastic gravitational-wave background(SGWB),which are characterized by the angular power *** find that a detector network can improve the measurement precision of anisotropies by at most fourteen orders of magnitude,depending on the angular *** doing so,we can enhance our understanding of the physical origins of SGWB,both in astrophysical and cosmological *** assess the prospects of the detector networks for measuring the parameters of angular power *** further find an inevitable effect of cosmic variance,which can be suppressed by a better angular resolution,strengthening the importance of configuring detector *** findings also suggest a potential detection of the kinematic dipole due to Doppler boosting of SGWB.

关键词： stochastic gravitational-wave background anisotropy space-based detector network

Production of N2O in two biologic nitrogen removal processes： a comparison between conventional and short-cut Nitrogen removal processes

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Frontiers of Environmental Science & Engineering 2014年第4期8卷 589-597页

作者： Youkui GONG Yongzhen PENG Shuying wang sai wang Shijiazhuang Institute of Railway Technology Shijiazhuang 050061 China School of Environmental and Energy Engineering Beijing University of Technology Beijing 100022 China

The N2O production in two nitrogen removal processes treating domestic wastewater was investigated in laboratory-scale aerobic-anoxic sequencing batch reactors （SBRs）. Results showed that N2O emission happened in the aerobic phase rather than in the anoxic phase. During the aerobic phase, the nitrogen conversion to N2O gas was 27.7% and 36.8% of NH＋-N loss for conventional biologic N-removal process and short-cut biologic N-removal process. The dissolved N2O was reduced to N2 in the anoxic denitrification phase. The N2O production rate increased with the increasing of nitrite concentration and ceased when NH＋-N oxidation was terminated. Higher nitrite accumulation resulted in higher NEO emission in the short-cut nitrogen removal process. Pulse-wise addition of 20 mg NO2 -N. L- 1 gave rise to 3-fold of N2O emission in the conventional N-removal process, while little change happened with 20 mg NOS-N L-1 was added to SBR1.

关键词： conventional N-removal process N2O short- cut N-removal process nitrite accumulation ammonia-oxidizing bacteria (AOB) denitrification

Constraints on the sum of neutrino masses using cosmological data including the latest extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample

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Chinese Physics C 2018年第6期42卷 134-140页

作者： sai wang Yi-Fan wang 夏冬梅 Department of Physics The Chinese University of Hong Kong Key Laboratory of Low-grade Energy Utilization Technologies & Systems of Ministry of Education of China College of Power EngineeringChongqing University

We investigate the constraints on the sum of neutrino masses（Σmv） using the most recent cosmological data, which combines the distance measurement from baryonic acoustic oscillation in the extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample with the power spectra of temperature and polarization anisotropies in the cosmic microwave background from the Planck 2015 data release. We also use other low-redshift observations,including the baryonic acoustic oscillation at relatively low redshifts, Type la supernovae, and the local measurement of the Hubble constant. In the standard cosmological constant A cold dark matter plus massive neutrino model,we obtain the 95% upper limit to be Σmv 〈0.129 eV for the degenerate mass hierarchy,Σmv 〈0.159 eV for the normal mass hierarchy, and Σmv 〈0.189 eV for the inverted mass hierarchy. Based on Bayesian evidence, we find that the degenerate hierarchy is positively supported, and the current data combination cannot distinguish between normal and inverted hierarchies. Assuming the degenerate mass hierarchy, we extend our study to non-standard cosmological models including generic dark energy, spatial curvature, and extra relativistic degrees of freedom, but find these models are not favored by the data.

关键词： neutrino mass mass hierarchy cosmological constraints

Beyond confined catalysis in porous materials

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National Science Review 2020年第6期7卷 994-995页

作者： Xiaoliang wang Pui Ching Lan sai wang Shengqian Ma Department of Chemistry University of South Florida

The assembly of active species into porous material has been extensively investigated in the past decades [1].Especially with the utilization of MetalOrganic Frameworks (MOFs), the techniques of encapsulating active species have been widely explored, which is beneficial to the unique aspects of MOFs,like tunable porosity, high capacity, open active sites and crystallinity nature, etc.

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From 1D Nanofibers to 3D Nanofibrous Aerogels: A Marvellous Evolution of Electrospun SiO_(2) Nanofibers for Emerging Applications

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Nano-Micro Letters 2022年第12期14卷 40-78页

作者： Cheng Liu sai wang Ni wang Jianyong Yu Yi-Tao Liu Bin Ding Innovation Center for Textile Science and Technology College of TextilesDonghua UniversityShanghai 201620People’s Republic of China

One-dimensional(1D)SiO_(2) nanofibers(SNFs),one of the most popular inorganic nanomaterials,have aroused widespread attention because of their excellent chemical stability,as well as unique optical and thermal *** is a straightforward and versatile method to prepare 1D SNFs with programmable structures,manageable dimensions,and modifiable properties,which hold great potential in many cutting-edge applications including aerospace,nanodevice,and *** this review,substantial advances in the structural design,controllable synthesis,and multifunctional applications of electrospun SNFs are *** begin with a brief introduction to the fundamental principles,available raw materials,and typical apparatus of electrospun *** then discuss the strategies for preparing SNFs with diverse structures in detail,especially stressing the newly emerging three-dimensional SiO_(2) nanofibrous *** continue with focus on major breakthroughs about brittleness-to-flexibility transition of SNFs and the means to achieve their mechanical *** addition,we showcase recent applications enabled by electrospun SNFs,with particular emphasis on physical protection,health care and water *** the end,we summarize this review and provide some perspectives on the future development direction of electrospun SNFs.

关键词： SiO_(2)nanofibers Nanofibrous aerogels Structural design Mechanical reinforcement Multifunctional applications

Novel scheme for interference avoidance in cognitive radio based cellular networks

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The Journal of China Universities of Posts and Telecommunications 2012年第1期19卷 69-76页

作者： wang sai XU Xiao-dong CHEN Xin TAO Xiao-feng wang Qiang Wireless Technology Innovation Institute Key Laboratory of Universal Wireless CommunicationMinistry of Education Beijing University of Posts and TelecommunicationsBeijing 100876China.

The cognitive radio （CR） technology is believed to improve the spectrum efficiency. However, the interference problem has become a critical issue due to the coexistence of primary systems and CR systems. In this paper, the interferences in CR based cellular networks are discussed. Interference scenarios are analyzed, considering different interference sources. Meanwhile, an improved model named ＇Cognitive Interference Ring＇ is introduced to describe the interference range of each secondary user （SU）. Depending on the above analysis, graph coloring based dynamic power allocation （GCDPA） scheme is proposed for interference avoidance. Simulation results demonstrate that in CR based cellular networks, the interferences to primary users （PUs） can be effectively mitigated with the proposed GCDPA scheme, and the system throughput and power efficiency are both improved.

关键词： CR interference analysis interference avoidance graph coloring power allocation cellular networks

Note on gauge invariance of second order cosmological perturbations

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Chinese Physics C 2021年第9期45卷 188-210页

作者： Zhe Chang sai wang Qing-Hua Zhu Theoretical Physics Division Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China

We study the gauge invariant cosmological perturbations up to the second *** demonstrate that there are infinite families of gauge inv ariant variables at both the first and seco nd *** conversion formulae among different families are verified to be described by a finite number of bases that are gauge *** the second order cosmological perturbations induced by the first order scalar perturbations,we explicitly represent their equations of motion in terms of the gauge invariant Newtonian,synchronous and hybrid variables,respectively.

关键词： cosmological perturbation theory physics of the early universe gauge invariance

Ultrafine-Grained Microstructure and Improved Mechanical Behaviors of Friction Stir Welded Cu and Cu–30Zn Joints

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Acta Metallurgica Sinica(English Letters) 2018年第8期31卷 878-886页

作者： Yan-Fei wang Jian An Kun Yin Ming-sai wang Yu-Sheng Li Chong-Xiang Huang School of Aeronautics and Astronautics Sichuan University Nano Structural Materials Center School of Materials Science and Engineering Nanjing University of Science and Technology

Ultra-strong joints of pure Cu and Cu–30Zn alloy were obtained by friction stir welding under flowing water. The effects of heat inputting condition and material characteristics on the morphologies, microstructures and mechanical properties of welding joints were studied. Defect-free stirring zones of pure Cu and Cu–30Zn were characterized by onion-ringed structure and plastic flowing bands, respectively. Both low stacking fault energy and fast cooling condition contributed to the formation of small recrystallized grains less than 1 μm in stirring zones. The welding joints in both materials exhibited enhanced mechanical performances due to ultrafine-grained microstructure in stirring zones and disappearance of soft heataffected-zone. The technique of digital image correlation was used to study the tensile deformation behaviors of welding joints and verify the improved tensile properties.

关键词： Friction stir welding Ultrafine grain Mechanical properties Stacking fault energy Digital image correlation(DIC)