Research on Multiband Impulse Radio UWB System based on PSWF in Multipath Fading Channel

Chen Lili,Dou Zheng,Yan Li,Lin Yun 보안공학연구지원센터(IJSIP) 2013 International Journal of Signal Processing, Image Vol.6 No.6

A fast and powerful aggregated Cauchy association test for joint analysis of multiple phenotypes

Lili Chen,Yajing Zhou 한국유전학회 2021 Genes & Genomics Vol.43 No.1

Background Pleiotropy is a widespread phenomenon in complex human diseases. Jointly analyzing multiple phenotypes can improve power performance of detecting genetic variants and uncover the underlying genetic mechanism. Objective This study aims to detect the association between genetic variants in a genomic region and multiple phenotypes. Methods We develop the aggregated Cauchy association test to detect the association between rare variants in a genomic region and multiple phenotypes (abbreviated as “Multi-ACAT”). Multi-ACAT frst detects the association between each rare variant and multiple phenotypes based on reverse regression and obtains variant-level p-values, then takes linear combination of transformed p-values as the test statistic which approximately follows Cauchy distribution under the null hypothesis. Results Extensive simulation studies show that when the proportion of causal variants in a genomic region is extremely small, Multi-ACAT is more powerful than the other several methods and is robust to bi-directional efects of causal variants. Finally, we illustrate our proposed method by analyzing two phenotypes [systolic blood pressure (SBP) and diastolic blood pressure (DBP)] from Genetic Analysis Workshop 19 (GAW19). Conclusion The Multi-ACAT computes extremely fast, does not consider complex distributions of multiple correlated phenotypes, and can be applied to the case with noise phenotypes.

Enhanced Mechanical Properties and Thermal Conductivity for GNPs/Al2024 Composites with In Situ SiC Nanorods

Lili Chen,Yushi Qi,Yanhan Fei,Zhiming Du 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10

In order to significantly enhance the performance of graphene in metal matrix composites, in situ SiC nanorods were successfullyfabricated to enhance graphene nanoplatelets (GNPs)-reinforced Al2024 composite, which was prepared by powdersemi-solid processing and friction stir processing. The SiC–GNPs dispersed in the Al matrix uniformly, SiC nanorodswere randomly grown on GNPs sheets in any direction, bridging GNPs as well as GNPs and the Al matrix. Meanwhile, theinterfacial bonding was effective. The hybrid reinforcement of SiC and GNPs endowed composites with superior mechanicalproperties and thermal conductivity. The in situ SiC nanorods transfer phonons and reduce phonon scattering effect inthe through-plane direction of GNPs, which conducive to heat transmission. The composite exhibits improved mechanicalproperties, maximum tensile strength and hardness of 589 MPa and 193 HV are obtained, with 1.0 wt% GNPs addition,respectively. The thermal conductivity of composite increases with the content of SiC–GNPs. When the content of SiC–GNPsreaches 1.5 wt%, the composite has significantly enhanced thermal conductivity (224 W m−1 K−1), which is 115% timeshigher than that of Al2024. Moreover, the effects of SiC–GNPs on the properties were discussed.

Study of the Effectiveness of the RVEs for Random Short Fiber Reinforced Elastomer Composites

Lili Chen,Boqin Gu,Jianfeng Zhou,Jiahui Tao 한국섬유공학회 2019 Fibers and polymers Vol.20 No.7

The effectiveness of the representative volume elements (RVEs) established by a modified random sequentialadsorption method for random short fiber reinforced elastomer composites (SFECs) was studied. The RVE is considered tobe effective when the RVE’s fiber orientation is isotropic. And the effectiveness of the RVEs was verified by evaluating themechanical properties in different loading directions based on the finite element method. The results show that the fibernumber N=4000 can be regarded as a steady threshold for the isotropy of the fiber orientation in RVEs with various fiberaspect ratios and dilute volume fraction.

Dose-Response Relationship between Alanine Aminotransferase Levels within the Reference Interval and Metabolic Syndrome in Chinese Adults

Peipei Wu,Shumei Wang,Qicai Chen,Lili Chen,Pengpeng Zhang,Juan Xiao,Xiaoxiao Chen,Meng Liu 연세대학교의과대학 2017 Yonsei medical journal Vol.58 No.1

Purpose: Elevation in serum alanine aminotransferase (ALT) levels is a biomarker for metabolic syndrome (MS); however, the relationshiphas not been fully investigated within the reference interval of ALT levels. Our objective was to explore the relationship between serum ALT levels within the reference interval and MS in Chinese adults. Materials and Methods: This cross-sectional study included 16028 adults, who attended routine health check-ups at Shengli OilfieldCentral Hospital from January 2006 to March 2012. The reference interval of serum ALT level was defined as less than 40 U/L. Logistic regression models and restricted cubic spline were used to evaluate the association of ALT with MS. Results: The prevalence of MS in the total population was 13.7% (6.4% for females and 18.4% for males). Multiple logistic regressionshowed that ALT levels were positively associated with MS after adjustment for potential confounding factors. The odds ratio of MS in the top quartile was 4.830 [95% confidence interval (CI): 2.980–7.829] in females and 3.168 (95% CI: 2.649–3.790) in males, compared with the ALT levels in the bottom quartile. The restricted cubic spline models revealed a positive non-linear dose-response relationship between ALT levels and the risk of MS in women (p for nonlinearity was 0.0327), but a positive linear dose-response relationship in men (p for nonlinearity was 0.0659). Conclusion: Serum ALT levels within the reference interval are positively associated with MS in a dose-response manner. ElevatedALT levels, even within the reference interval, may reflect early dysmetabolic changes.

Wind characteristics of a strong typhoon in marine surface boundary layer

Lili Song,Q. S. Li,Wenchao Chen,Peng Qin,Haohui Huang,Y.C. He 한국풍공학회 2012 Wind and Structures, An International Journal (WAS Vol.15 No.1

High-resolution wind data were acquired from a 100-m high offshore tower during the passage of Typhoon Hagupit in September, 2008. The meteorological tower was equipped with an ultrasonic anemometer and a number of cup anemometers at heights between 10 and 100 m. Wind characteristics of the strong typhoon, such as mean wind speed and wind direction, turbulence intensity, turbulence integral length scale, gust factor and power spectra of wind velocity, vertical profiles of mean wind speed were investigated in detail based on the wind data recorded during the strong typhoon. The measured results revealed that the wind characteristics in different stages during the typhoon varied remarkably. Through comparison with non-typhoon wind measurements, the phenomena of enhanced levels of turbulence intensity, gust factors, turbulence integral length scale and spectral magnitudes in typhoon boundary layer were observed. The monitored data and analysis results are expected to be useful for the wind-resistant design of offshore structures and buildings on seashores in typhoon-prone regions.

Morphology Controlled Synthesis of Octahedral Covalent Imine Frameworks Through Acid Modulated Aldehyde-Amine Polycondensation

Lili Pan,Zihua Chen,Wenxiu De,Guangjie Yang,Xikui Liu 한국고분자학회 2016 Macromolecular Research Vol.24 No.4

The past decades have witnessed significant advance in the synthesis of covalent organic frameworks (COFs), however, their formation and morphology revolution mechanism have been rarely reported. Here, through an acid modulated dynamic covalent chemistry approach, pure and uniform micro-octahedral covalent imine frameworks were obtained for the first time. Formation mechanism based on the stacking of initially formed two-dimensional nanoplates followed by surface smoothing enabled by the dynamic nature of imine bonding was proposed. Furthermore, we revealed for the first time that nonstoichiometric method can be applied to the synthesis of covalent organic frameworks. Thus we provide novel strategy for the morphology control COFs which will surely facilitate their application in energy-related area.

Study of the Permeability of Tomato Pericarp Etched by Low-energy Ion Beams Based on α-particles Irradiation

Lili Zhang,Lianyun Chen,Xue Xu,Qing Huang,Yuejin Wu 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.3

Low-energy ion beam bio-technology has been applied in the biological field and has gained remarkable success in crop and microbe breeding. However, to understand how low-energy ion beams interact with biological materials remains a challenge for researchers who work for the development of ion-beam bio-technology. In this work,tomato pericarp was used as the target sample to study the effect of ion beams on the permeability of biological objects. A series of experiments were conducted via irradiating tomato pericarp samples with low-energy (10 keV ~ 25 keV)ion beams followed by measuring the pericarp’s permeability using transmissive α particles. The transmissive spectra of α particles and the measurement of the tip number in CR39gave a quantitative evaluation of the sputtering effect caused by low-energy ions. Meanwhile, natural red dye was used to examine the permeability of irradiated tomato pericarp samples. It was found that the sputtering effect is not only proportional to the ion energy and dose, but dependent on the ion type as well. The damage caused by Ar ions due to sputtering was much more severe than that caused by N ions sputtering with the same dose. Therefore,this study not only demonstrates the permeability difference of biological membranes before and after ion irradiation,but also provides the information on how to optimize the experimental conditions for application of the low-energy ion beam in biology.

Filled Skutterudites: from Single to Multiple Filling

Lili Xi,Wenqing Zhang,Lidong Chen,Jihui Yang 한국세라믹학회 2010 한국세라믹학회지 Vol.47 No.1

This paper shortly reviews our recent work on filled skutterudites, which are considered to be one of the most promising thermoelectric (TE) materials due to their excellent power factors and relatively low thermal conductivities. The filled skutterudite system also provides a platform for studying void filling physics/chemistry in compounds with intrinsic lattice voids. By using ab initio calculations and thermodynamic analysis, our group has made progresses in understanding the filling fraction limit (FFL) for single fillers in CoSb3, and ultra-high FFLs in a few alkali-metal-filled CoSb3 have been predicted and then been confirmed experimentally. FFLs in multiple-element-filled CoSb3 are also investigated and anonymous filling behavior is found in a few specific systems. The calculated and measured FFLs, in both single and multiple-filled CoSb3 systems, show good accordance so far. The thermal transport properties can be understood qualitatively by a phonon resonance scattering model, and it seems that a scaling rule may exist between the lattice thermal resistivity and the resonance frequency of filler atoms in filled system. Even though a few things become clear now, there are still many unsolved issues that call for further work.

Optical temperature sensing properties of Yb3+/Tm3+ co-doped NaLuF4 crystals

Lili Tong,Xiangping Li,Ruinian Hua,Lihong Cheng,Jiashi Sun,Jinsu Zhang,Sai Xu,Hui Zheng,Yanqiu Zhang,Baojiu Chen 한국물리학회 2017 Current Applied Physics Vol.17 No.7

Yb3þ/Tm3þ and Yb3þ/Er3þ co-doped NaLuF4 crystals were synthesized by a facile hydrothermal method. The optical temperature sensing properties of Tm3þ based upon its two thermally coupled energy levels 3F2, 3 and 3H4 were systematically investigated by means of fluorescence intensity ratio (FIR) technique. The 980 nm laser-induced thermal effect on Tm3þ doped NaLuF4 crystals was studied by using Er3þ doped sample as thermal probe. The temperature sensitivity of Tm3þ in NaLuF4: Yb3þ/Tm3þ crystals shows a nonlinear dependence on temperature, and the maximum value is about 0.00045 K『1 at 600 K. The accuracy and reliability of the optical thermometry based on Tm3þ in NaLuF4: Yb3þ/Tm3þ crystals has been checked by using Yb3þ/Er3þ co-doped sample as temperature sensing unit. The results demonstrate that NaLuF4: Yb3þ/Tm3þ crystals have good sensing stability and may have potential application for the optical thermometry.