检索结果-南通市图书馆

Ionic liquids in transdermal drug delivery system: Current applications and future perspectives

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2023年第3期34卷 113-121页

作者： Yang Zhang Chao Liu Jiaqi Wang Shoujun Ren Yilin Song Peng Quan Liang Fang Department of Pharmaceutical Sciences Shenyang Pharmaceutical UniversityShenyang 110016China

The transdermal drug delivery(tdd) shows considerable advantages over other administration pathways.However, conventional enhancing permeation methods face a series of challenges owing to barrier function provided by the skin, of which enhancing abilities either are so strong that it results in toxicity and irritation, or too weak to achieve desirable therapeutical effects. To address these issues, it is an urgent need to develop a novel method to overcome the limitations of current measures. Fortunately, in the preceding decades, ionic liquids(ILs) have been extensively studied and increasingly applied in pharmaceutical drug delivery due to their unique physicochemical and biological properties. What is more, tunability of structure resolves the challenges in processing active pharmaceutical ingredient(API) formulation, such as polymorphism and poor solubility of drugs. Thus, the presence of ILs provides an ample design space for the transdermal drug delivery system(tddS). This review discusses the shortcomings of conventional enhancing permeation methods and introduces the application of ILs in transdermal delivery from three aspects: i) ILs are applied as enhancers to weaken the barrier function of the stratum corneum(SC). ii) As counterions, ILs are combined with API to modify the physicochemical properties of drugs. iii) ILs assist in the design of transdermal preparation for perfecting formulation. This review comprehensively introduces the major breakthroughs made in the applications of ILs, which can serve as guidance to provide novel ideas for formulation scientists who hit the bottleneck in the development of tdd.

关键词： tdd Ionic liquids Skin Permeation enhancers Physicochemical properties

tdd-net: a tiny defect detection network for printed circuit boards

在线全文

学校读者我要写书评

暂无评论

CAAI Transactions on Intelligence Technology 2019年第2期4卷 110-116页

作者： Runwei Ding Linhui Dai Guangpeng Li Hong Liu Key Laboratory of Machine Perception Peking University Shenzhen Graduate School People’s Republic of China Shenzhen Skyworth-RGB Electronic CO. Ltd. People’s Republic of China

Tiny defect detection (tdd) which aims to perform the quality control of printed circuit boards (PCBs) is a basic and essential task in the production of most electronic products. Though significant progress has been made in PCB defect detection, traditional methods are still difficult to cope with the complex and diverse PCBs. To deal with these problems, this article proposes a tiny defect detection network (tdd-Net) to improve performance for PCB defect detection. In this method, the inherent multi-scale and pyramidal hierarchies of deep convolutional networks are exploited to construct feature pyramids. Compared with existing approaches, the tdd-Net has three novel changes. First, reasonable anchors are designed by using k-means clustering. Second, tdd-Net strengthens the relationship of feature maps from different levels and benefits from low-level structural information, which is suitable for tiny defect detection. Finally, considering the small and imbalance dataset, online hard example mining is adopted in the whole training phase in order to improve the quality of region-of-interest (ROI) proposals and make more effective use of data information. Quantitative results on the PCB defect dataset show that the proposed method has better portability and can achieve 98.90% mAP, which outperforms the state-of-arts. The code will be publicly available.

关键词： tdd PCBs tdd-Net

tdd reciprocity calibration for multi-user massive MIMO systems with iterative coordinate descent

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2016年第10期59卷 93-102页

作者： Hao WEI Dongming WANG Jiangzhou WANG Xiaohu YOU National Mobile Communications Research Laboratory Southeast University School of Engineering and Digital Arts University of Kent

For massive multiple-input multiple-output(MIMO) antenna systems, time division duplexing(tdd) is preferred since the downlink precoding matrix can be obtained through the uplink channel estimation,thanks to the channel reciprocity. However, the mismatches of the transceiver radio frequency(RF) circuits at both sides of the link make the whole communication channel non-symmetric. This paper extends the total least square(TLS) method to the case of self-calibration, where only the antennas of the access points(APs) are involved to exchange the calibration signals with each other and the feedback from the user equipments(UEs)is not required. Then, the proof of the equivalence between the TLS method and the least square(LS) method is presented. Furthermore, to avoid the eigenvalue decomposition required by these two methods to obtain the calibration coefficients, a novel algorithm named as iterative coordinate descent(ICD) method is proposed.Theoretical analysis and simulation results show that the ICD method significantly reduces the complexity and achieves almost the same performance of the LS method.

关键词： tdd reciprocity calibration total least squares coordinate descent large-scale MIMO

A Comprehensive Survey of tdd-Based Mobile Communications Systems from TD-SCDMA 3G to TDLTE-Advanced 4G and 5G directions

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

China Communications 2015年第2期12卷 40-60页

作者： CHEN Shanzhi SUN Shaohui WANG Yingmin XIAO Guojun Rakesh Tamrakar State Key Laboratory of Wireless Mobile Communications China Academy of Telecommunications Technology(CATT) Datang Telecom Technology & Industry Group

tdd(Time Division Duplex) is one of the two duplex modes.TD-SCDMA(Time division Synchronous CDMA) is the first tdd-based cellular mobile system which is commercialized in wide area and large scale and TD-SCDMA is also the first cellular mobile system which adopted smart antenna technology,also called as beamforming.As the long term evolution of TD-SCDMA,TDLTE(A)(Time Division-Lone Term Evolution,and TD-LTE Advanced) introduced OFDM(Orthogonal Frequency Division Multiplexing)and enhanced smart antenna technology together with MIMO(Multiple Input Multiple Output),which are adopted by LTE FDD(Frequency Division Duplex) either.It is indicated that TD-SCDMA and TD-LTE(A)have opened a sustainable utilization era of tdd and smart antenna Technologies in the wireless mobile communication.This paper aims to present a systematic introduction to tdd-based mobile communications from TD-SCDMA to TD-LTE and beyond and its comparisons to FDD,with particular focuses on tdd key technologies,principles of tdd cellular mobile systems,tdd evolution path,and future tdd 5G directions.We hope that this paper will provide a comprehensive overview of tdd technology upgrade and its standard evolution,and serve as a valuable reference for research on 5G mobile communication systems.It is believed that tdd will play more important role in 5G.

关键词： TD-SCDMA系统蜂窝移动通信系统 tdd 基础智能天线技术蜂窝移动系统时分双工 3G

Design and Implementation of a tdd-Based 128-Antenna Massive MIMO Prototype System

在线全文

学校读者我要写书评

暂无评论

China Communications 2017年第12期14卷 162-187页

作者： Xi Yang Wenjun Lu Ning Wang Karl Nieman Chao-Kai Wen Chuan Zhang Shi Jin Xiaomin Mu Ian Wong Yongming Huang Xiaohu You National Mobile Communications Research Laboratory Southeast University Nanjing 210096 China Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and Telecommunications Nanjing 210003 China School of Information Engineering Zhengzhou University Zhengzhou 450001 China National Instruments Austin 78759 Texas USA Institute of Communications Engineering National Sun Yat-sen University Kaohsiung 804 Taiwan China

Owing to the dramatic mobile IP growth,the emerging Internet of Things,and cloud-based applications,wireless networking is witnessing a paradigm shift.By fully exploiting spatial degrees of freedom,massive multiple-input-multiple-output(MIMO) systems promise significant gains in data rates and link reliability.Although the research community has recognized the theoretical benefits of these systems,building the hardware of such complex systems is a challenge in practice.This paper presents a time division duplex(tdd)-based 128-antenna massive MIMO prototype system from theory to reality.First,an analytical signal model is provided to facilitate the setup of a feasible massive MIMO prototype system.Second,a link-level simulation consistent with practical tddbased massive MIMO systems is conducted to guide and validate the massive MIMO system design.We design and implement the tddbased 128-antenna massive MIMO prototype system with the guidelines obtained from the link-level simulation.Uplink real-time video transmission and downlink data transmission under the configuration of multiple single-antenna users are achieved.Comparisons withstate-of-the-art prototypes demonstrate the advantages of the proposed system in terms of antenna number,bandwidth,latency,and throughput.The proposed system is also equipped with scalability,which makes the system applicable to a wide range of massive scenarios.

关键词： massive MIMO prototyping sys-tem software defined radio tdd

Quantum Correlations in Ising-XYZ Diamond Chain Structure under an External Magnetic Field

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2015年第10期32卷 9-13页

作者： Faizi E. Eftekhari H. Department of Physics Azerbaijan Shahid Madani University

We consider an entangled Ising-XY Z diamond chain structure. Quantum correlations for this model are inves- tigated by using quantum discord and trace distance discord. Quantum correlations are obtained for different values of the anisotropy parameter, magnetic field and temperature. By comparison between quantum correlations, we show that the trace distance discord is always larger than quantum discord. Finally, some novel effects such as increasing the quantum correlations with temperature and constructive role of anisotropy parameter, which may play to the quantum correlations, are observed.

关键词： tdd Quantum Correlations in Ising-XYZ Diamond Chain Structure under an External Magnetic Field

Channel estimation in tdd mode

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2006年第3期13卷 34-37页

作者： ZHANG Yi GU Jian YANG Da-cheng School of Telecommunication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

An efficient solution is proposed in this article for the channel estimation in time division duplex （tdd） mode wireless communication systems. In the proposed solution, the characteristics of fading channels in tdd mode systems are fully exploited to estimate the path delay of the fading channel. The corresponding amplitude is estimated using the minimum mean square error （MMSE） criterion. As a result, it is shown that the proposed novel solution is more accurate and efficient than the traditional solution, and the improvement is beneficial to the performance of Joint Detection.

关键词： channel estimation MMSE tdd

Analysis of QTLs for the Trichome Density on the Upper and Downer Surface of Leaf Blade in Soybean [Glycine max (L.) Merr.]

在线全文

学校读者我要写书评

暂无评论

Agricultural Sciences in China 2009年第5期8卷 529-537页

作者： DU Wei-jun YU De-yue FU San-xiong National Center for Soybean Improvement/National Key Laboratory of Crop Genetics and Germplasm Enhancement/Nanjing Agricultural University Nanjing 210095 P.R. China College of Agronomy Shanxi Agricultural University Taigu 030801 P.R.China

Trichomes （plant hairs） are present on nearly all land plants and are known to play important roles in plant protection, specifically against insect herbivory, drought, and UV radiation. The identification of quantitative trait loci （QTL） associated with trichome density should help to interpret the molecular genetic mechanism of soybean trichome density. 184 recombinant inbred lines （RILs）, derived from a cross between soybean cultivars Kefeng 1 and Nannong 1138-2 were used as segregating population for evaluation of TDU （trichome density on the upper surface of leaf blade） and tdd （trichome density on the downer surface of leaf blade）. A total of 15 QTL were detected on molecular linkage groups （MLG） A2, Dla, Dlb, E and H by composite interval mapping （CIM） and among all the QTL, qtuA2-1, qtuD 1 a-1, qtuD lb-2, qtuH-2 qtuE-1, qtddlb-2, and qtdH- 2 were affirmed by multiple interval mapping （MIM）. The contribution ofphenotypic variance of qtuH-2 was 31.81 and 29.4% by CIM and MIM, respectively, suggesting it might be major gene Ps loci. Only 10 pairs of main QTL interactions for TDU were detected, explained a range of 0.2-5.1% of phenotypic variations for each pair for a total of 22.8%. The QTL on MLG Dlb affecting trichome density were mapped near to Rsc-7 conditioning resistance to SMV （soybean mosaic virus）. This study showed that the genetic mechanism of trichome density was the mixed major gene and polygene inheritance, and also suggested that the causal nature between trichome density and other agronomic traits.

关键词： soybean [Glycine max （L.） Merr.] TDU tdd RI Ls QTL analysis

Antenna calibration using channel prediction for time-varying channels

在线全文

学校读者我要写书评

暂无评论

Journal of Modern Transportation 2012年第4期20卷 213-219页

作者： Yamin SONG Xia LEI Zhaofu KONG Binhong DONG National Key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of China

Traditional antenna calibration methods for time division duplex （tdd） systems asSume that the flee-space channel remains the same during calibration, which is unreasonable under the high-speed rail and other time-varying channel scenarios, and will cause calibration error due to time variability. This paper proposes an antenna calibration method for time-varying channels. In the proposed method, the transceiver first sequentially sends a pilot signal to ob- tain equivalent do^vnlink and uplink channel responses. Then, by predicting the downlink （uplink） channel response fed back from the receiver using the channel prediction algorithm, the transmitter obtains the channel response correspond- ing to the channel response on uplink （downlink）. Finally, the transmitter calculates the transmission calibration factor through the prediction value. Compared with the traditional antenna calibration method, this method can improve the accuracy of the calibration factor. Simulation results show that the performance degradation of antenna calibration can be caused by time-varying channels and the proposed method can well compensate for the performance loss and sig- nificantly improve the antenna calibration performance for time-varying channels.

关键词： tdd channel reciprocity time-varying channel channel prediction antenna calibration