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Search Results: 1 - 10 of 104305 matches for " Qingfeng Zhang "
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A Learning-based Adaptive Routing Tree for Wireless Sensor Networks
Ying Zhang,Qingfeng Huang
Journal of Communications , 2006, DOI: 10.4304/jcm.1.2.12-21
Abstract: One of the most common communication patterns in sensor networks is routing data to a base station, while the base station can be either static or mobile. Even in static cases, a static spanning tree may not survive for a long time due to failures of sensor nodes. In this paper, we present an adaptive spanning tree routing mechanism, using real-time reinforcement learning strategies. We demonstrate via simulation that without additional control packets for tree maintenance, adaptive spanning trees can maintain the “best” connectivity to the base station, in spite of node failures or mobility of the base station. And by using a general constraint-based routing specification, one can apply the same strategy to achieve load balancing and to control network congestion effectively in real time.
Sums of the triple divisor function over values of a ternary quadratic form
Qingfeng Sun,Deyu Zhang
Mathematics , 2015,
Abstract: Let $\tau_3(n)$ be the triple divisor function which is the number of solutions of the equation $d_1d_2d_3=n$ in natural numbers. It is shown that $$ \sum_{1\leq n_1,n_2,n_3\leq \sqrt{x}}\tau_3(n_1^2+n_2^2+n_3^2)=c_1x^{\frac{3}{2}}(\log x)^2+ c_2x^{\frac{3}{2}}\log x +c_3x^{\frac{3}{2}} +O_{\varepsilon}(x^{\frac{11}{8}+\varepsilon}) $$ for some constants $c_1$, $c_2$ and $c_3$.
Dimensional Synthesis for Wide-Band Bandpass Filters with Quarter-Wavelength Resonators
Qingfeng Zhang;Yi-Long Lu
PIER B , 2009, DOI: 10.2528/PIERB09080501
Abstract: This paper presents a dimensional synthesis method for designing wide-band quarter-wavelength resonator bandpass filters. In this synthesis method, an alternative lowpass prototype filter and the edge frequency mapping method are proposed and applied. The improved K- and J-inverter model with the exponent- weighted turns ratio is also proposed in order to incorporate the frequency dependence of inverters. Based on the edge frequency mapping method and the improved inverter model, an iterative dimensional synthesis procedure is then presented. As design examples, a four-pole rectangular coaxial bandpass filter with 63% fractional bandwidth is designed and fabricated. The simulation and measurement results show good equal ripple performance in the passband.
Enhanced-SNR Impulse Radio Transceiver based on Phasers
Babak Nikfal,Qingfeng Zhang,Christophe Caloz
Physics , 2014,
Abstract: The concept of SNR enhancement in impulse radio transceivers based on phasers of opposite chirping slopes is introduced. It is shown that signal to-noise radio (SNR) enhancements by factors M2 and M are achieved for burst noise and Gaussian noise, respectively, where M is the stretching factor of the phasers. An experimental demonstration is presented, using stripline cascaded C-section phasers, where SNR enhancements in agreement with theory are obtained. The proposed radio analog signal processing transceiver system is simple, low-cost and frequency scalable, and may therefore be suitable for broadband impulse radio ranging and communication applications.
Design of Dispersive Delay Structures (DDSs) Formed by Coupled C-Sections Using Predistortion with Space Mapping
Qingfeng Zhang,John W. Bandler,Christophe Caloz
Physics , 2013, DOI: 10.1109/TMTT.2013.2287678
Abstract: The concept of space mapping is applied, for the first time, to the design of microwave dispersive delay structures (DDSs). DDSs are components providing specified group delay versus frequency responses for real-time radio systems. The DDSs considered in this paper are formed by cascaded coupled C-sections. It is first shown that aggressive space mapping does not provide sufficient accuracy in the synthesis of DDSs. To address this issue, we propose a predistortion space mapping technique. Compared to aggressive space mapping, this technique provides enhanced accuracy, while compared to output space mapping, it provides greater implementation simplicity. Two full-wave and one experimental examples are provided to illustrate the proposed predistortion space mapping technique.
Planar Reflective Phaser and Synthesis for Radio Analog Signal Processing (R-ASP)
Lianfeng Zou,Qingfeng Zhang,Christophe Caloz
Physics , 2014,
Abstract: A planar reflective phaser based on an open-ended edge-coupled-line structure is proposed. This phaser is the first reported phaser that combines the benefits of high resolution, inherent to cross-coupled resonator reflective phasers, and of compactness, inherent to planar circuits. A 4-ns swing 4.9-5.5 GHz quadratic phase (linear group delay) 4th-order microstrip phaser is synthesized and experimentally demonstrated. Given its advantages, this phaser may find vast applications in Radio Analog Signal Processing (R-ASP) systems.
Concentrated Growth Factor from Autologous Platelet Promotes Hair Growth in Androgenetic Alopecia  [PDF]
Poh-Ching Tan, Yun Xie, Wei Wu, Peiqi Zhang, Yiming Gao, Kai Liu, Shuangbai Zhou, Qingfeng Li
Journal of Biomedical Science and Engineering (JBiSE) , 2019, DOI: 10.4236/jbise.2019.123014
Abstract: Studies have shown that platelet concentrates can induce the proliferation of the dermal papilla and the vascularization of the perifollicular tissue, as well as accelerate the telogen-to-anagen transition, thereby promoting the regrowth of hair improving the appearance of hair loss. Herein, we report on the application of a new, modified form of platelet concentrates, namely, concentrated growth factors (CGFs), in 15 cases of androgenetic alopecia (AGA). 15 cases of androgenetic alopecia were treated with the use of monthly, subcutaneous injections of autologous CGF in the scalp. A total of 3 injections were administered 4 weeks apart, and the patients were followed up for 6 months. Assessments were performed before the treatments and at 4, 8, 12 and 24 weeks after the first treatment. The treatment outcomes were assessed by taking macroscopic photographs and trichoscopic photomicrographs, as well as by using the Global Aesthetic Improvement Scale (GAIS) and the patient satisfaction survey. In order to determine the safety of the treatment, the injection area was observed for signs of infection or mass evaluation. The photographs showed significant improvement in hair appearance after injections of CGF. The hair photomicrographs showed that CGF promoted the regrowth of hair in balding areas, with an increased hair density and an increased ratio of terminal to vellus hair. The GAIS suggested that CGF treatments were effective in treating AGA, and the majority of patients were satisfied with their improvement. In addition, treatments resulted in a faster rate of hair growth and a decrease in the greasy and unpleasant sensation of the hair of the patients. At the last visit, none of the 15 patients reported experiencing side-effects during the follow-up period. To conclude, the application of CGF can be an effective method in the treatment of androgenetic alopecia.
No miRNA were found in Plasmodium and the ones identified in erythrocytes could not be correlated with infection
Xiangyang Xue, Qingfeng Zhang, Yufu Huang, Le Feng, Weiqing Pan
Malaria Journal , 2008, DOI: 10.1186/1475-2875-7-47
Abstract: Of 132 small RNA sequences, no Plasmodium-specific miRNAs have been found. However, a human miRNA, miR-451, was highly expressed, comprising approximately one third of the total identified miRNAs. Further analysis of miR-451 expression and malaria infection showed no association between the accumulation of miR-451 in Plasmodium falciparum-iRBCs, the life cycle stage of P. falciparum in the erythrocyte, or of P. berghei in mice. Moreover, treatment with an antisense oligonucleotide to miR-451 had no significant effect on the growth of the erythrocytic-stage P. falciparum.Short RNAs from a mixed-stage of P. falciparum-iRBC were separated in a denaturing polyacrylamide gel and cloned into T vectors to create a cDNA library. Individual clones were then sequenced and further analysed by bioinformatics prediction to discover probable miRNAs in P. falciparum-iRBC. The association between miR-451 expression and the parasite were analysed by Northern blotting and antisense oligonucleotide (ASO) of miR-451.These results contribute to eliminate the probability of miRNAs in P. falciparum. The absence of miRNA in P. falciparum could be correlated with absence of argonaute/dicer genes. In addition, the miR-451 accumulation in Plasmodium-infected RBCs is independent of parasite infection. Its accumulation might be only the residual of erythroid differentiation or a component to maintain the normal function of mature RBCs.MicroRNAs (miRNAs), a newly discovered class of endogenous ~21 nucleotide regulatory non-coding small RNAs, post-transcriptionally regulated gene expression in eukaryotes by targeted RNA degradation and translational arrest [1]. Similarly to short interfering RNAs (siRNAs), miRNAs are produced in the cytoplasm from a precursor, which contains an imperfectly matched inverted repeat forming a partial double-stranded region, by the ribonuclease, dicer. One strand of the resulting miRNA duplex intermediate is then recruited by the argonaute nuclease, an enzyme involve
A high-resolution climatic change since Holocene inferred from multi-proxy of lake sediment in westerly area of China
QingFeng Jiang,Ji Shen,XingQi Liu,EnLou Zhang,XiaYun Xiao
Chinese Science Bulletin , 2007, DOI: 10.1007/s11434-007-0245-6
Abstract: Multi-proxy data are presented and a discuss is made of paleoclimatic and paleoenvironmental changes during Holocene from a 225-cm-long sediment core from Wulungu Lake, located in westerly area of China. The chronology is constructed from six AMS radiocarbon dates on the bulk organic matter. Analyses of pollen, TOC, TN, δ 13Corg, ostracod assemblages and the shell stable isotopes, suggest Holocene climate pattern as follows: temperate and dry (10.0–7.6 cal. ka BP)-warm and wet (7.6–5.3 cal. ka BP)-warm and moist (5.3–3.6 cal. ka BP)-temperate and dry (3.6–2.1 cal. ka BP)-temperate and moist (2.1–1.3 cal. ka BP)-cool and dry (1.3 cal. ka BP—present). With the climatic change, Wulungu Lake experienced two large-scale retreat (5.3–3.6 cal. ka BP and 1.3 cal. ka BP—present) and an obvious transgression (7.6–5.3 cal. ka BP). The records of climatic and environmental evolution of Wulungu Lake were in good accordance with those of adjacent areas. It responded to regional environmental change, global abrupt climate events and followed the westerly climate change mode.
Roles of intracellular fibroblast growth factors in neural development and functions
Xu Zhang,Lan Bao,Liu Yang,QingFeng Wu,Shuai Li
Science China Life Sciences , 2012, DOI: 10.1007/s11427-012-4412-x
Abstract: Fibroblast growth factors (FGFs) can be classified as secretory (FGF1-10 and FGF15-23) or intracellular non-secretory forms (FGF11-14). Secretory forms of FGF and their receptors are best known for their regulatory roles in cell growth, differentiation and morphogenesis in the early stages of neural development. However, the functions of intracellular FGFs remain to be explored. FGF12 and FGF14 are found to interact with voltage-gated sodium channels, and regulate the channel activity in neurons. FGF13 is expressed in primary sensory neurons, and is colocalized with sodium channels at the nodes of Ranvier along the myelinated afferent fibers. FGF13 is also expressed in cerebral cortical neurons during the late developmental stage. A recent study showed that FGF13 is a microtubule-stabilizing protein required for regulating the neuronal development in the cerebral cortex. Thus, non-secretory forms of FGF appear to have important roles in the brain, and it would be interesting to further investigate the functions of intracellular FGFs in the nervous system and in neural diseases.
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