检索结果-南通市图书馆

Femtosecond measurement of third-order optical nonlinearities in Bi_2O_3-B_2O_3-BaO glasses

在线全文

学校读者我要写书评

暂无评论

Chinese Optics Letters 2010年第1期8卷 70-73页

作者：徐铁峰陈飞飞戴世勋聂秋华沈祥王训四 college of information science and engineering Ningbo University

We present the measurement of the third-order nonlinearity of Bi203-B^O3-BaO glasses using the single Z-scan method with femtosecond laser pulses at 750 - 850 nm. Both third-order nonlinear refraction γ and two photon absorption coefficient β are investigated. The γ shows an increasing tendency with increasing BaO content, and the largest value is estimated to be 7.2×10^-14 cm^2/W, which is as large as those of chalcogenide glasses. The dependence of 13 on the normalized photon energy is studied.

关键词： Glass Glass lasers Nonlinear optics Photons Pulsed laser applications

Tm^(3+)-doped tellurite glass with Yb^(3+) energy sensitized for broadband amplifier at 1400–1700 nm bands

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2008年第6期26卷 907-911页

作者：王训四聂秋华徐铁峰沈祥戴世勋盖娜 college of information science and engineering Ningbo University

A kind of novel experiment was disclosed as it possessed two bands of fluorescence emission at 1.4 and 1.6 μm, which were perfectly complimentary to the current C band of optic communication. The fluorescence was based on energy transfer and up-conversion processes between Tm^3＋ and Yb^3＋ under direct pumping of 975 nm LD. The spectra and lifetimes of Tm^3＋ fluorescence in the tellurite glass were described. The corresponding fluorescence characteristics and energy migration process were analyzed by the method of lifetime and intensity comparison. The mechanism of the up-conversion based IR fluorescence was presented upon analyzing the multi-photon pumping process. The potential advantages of Tm^3＋/Yb^3＋ co-doped tellurite glass as amplifier material were concluded.

关键词： broadband amplifier Tm^3+-doped amplifier tellurite glass energy transfer rare earths

Detecting high-dimensional multipartite entanglement via some classes of measurements

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2018年第2期27卷 249-254页

作者：刘璐高亭闫凤利 college of Mathematics and information science Hebei Normal University college of Physics science and information engineering Hebei Normal University

Mutually unbiased bases, mutually unbiased measurements and general symmetric informationally complete measure- ments are three related concepts in quantum information theory. We investigate multipartite systems using these notions and present some criteria detecting entanglement of arbitrary high dimensional multi-qudit systems and multipartite sys- tems of subsystems with different dimensions. It is proved that these criteria can detect the k-nonseparability （k is even） of multipartite qudit systems and arbitrary high dimensional multipartite systems of m subsystems with different dimensions. We show that they are more efficient and wider of application range than the previous ones. They provide experimental implementation in detecting entanglement without full quantum state tomography.

关键词： detection of entanglement multipartite quantum states mutually unbiased bases mutually unbi-ased measurements general symmetric informationally complete measurements

Low-cost intelligent reflecting surface aided Terahertz multiuser massive MIMO: design and analysis

在线全文

学校读者我要写书评

暂无评论

science China(information sciences) 2021年第10期64卷 73-87页

作者： Guanghua YU Xiaoming CHEN Xiaodan SHAO Caijun ZHONG college of information science and Electronic engineering Zhejiang University

Terahertz(THz) multiuser massive multiple-input multiple-output(MIMO) has been envisioned as a promising technique to support massive connectivity in next-generation wireless networks. However,due to ultra-high frequency band, the path attenuation of THz channels is extremely severe, resulting in limited wireless coverage. In this paper, we propose an intelligent reflecting surface(IRS)-assisted THz multiuser massive MIMO technique to enhance coverage. First, we design an IRS-assisted THz communication framework with a low-cost sub-connected hybrid precoding architecture, including uplink data transmission and downlink data transmission. In particular, precoding errors due to the limitations of physical devices and environments are taken into consideration. Then, we derive the closed-form expressions for uplink and downlink spectral efficiencies, and reveal the impacts of system parameters. Finally, we conduct extensive simulations to verify the effectiveness of the proposed IRS-assisted THz multiuser massive MIMO technique.

关键词： THz communication IRS massive MIMO precoding error coverage enhancement

Power-efficient dual-edge implicit pulse-triggered flip-flop with an embedded clock-gating scheme

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Frontiers of information Technology & Electronic engineering 2016年第9期17卷 962-972页

作者： Liang GENG Ji-zhong SHEN Cong-yuan XU college of information science & Electronic engineering Zhejiang University

A novel dual-edge implicit pulse-triggered flip-flop with an embedded clock-gating scheme(DIFF-CGS) is proposed, which employs a transmission-gate-logic(TGL) based clock-gating scheme in the pulse generation stage. This scheme conditionally disables the inverter chain when the input data are kept unchanged, so redundant transitions of delayed clock signals and internal nodes of the latch are all eliminated, leading to low power efficiency. Based on SMIC 65 nm technology, extensive post-layout simulation results show that the proposed DIFF-CGS gains an improvement of 41.39% to 56.21% in terms of power consumption, compared with its counterparts at 10% data-switching activity. Also, full-swing operations in both implicit pulse generation and the static latch improve the robustness of the design. Thus, DIFF-CGS is suitable for low-power applications in very-large-scale integration(VLSI) designs with low data-switching activities.

关键词： Low power Flip-flop Implicit Clock-gating scheme Dual-edge

Robust federated learning for edge-intelligent networks

在线全文

学校读者我要写书评

暂无评论

science China(information sciences) 2022年第3期65卷 246-254页

作者： Zhihe GAO Xiaoming CHEN Xiaodan SHAO college of information science and Electronic engineering Zhejiang University

The rapid development of machine learning and wireless communication is creating a new paradigm for future networks, namely edge-intelligent networks. Specifically, data generated by terminal devices is processed via machine learning at the edge of wireless networks, but not at the cloud. Owing to the growing concern for privacy information sharing, federated learning, as a new branch of machine learning,is appealing in edge-intelligent networks. For federated learning, the wireless transmission capabilities under practical conditions, e.g., imperfect channel state information(CSI), have a great impact on the accuracy of global aggregation of local model updates. Therefore, it is very important to enhance the robustness of communication for federated learning. In order to realize robust communication in the presence of channel uncertainty, we propose a robust federated learning algorithm for edge-intelligent networks, including device selection, transmit power allocation, and receive beamforming. Simulation results validate the robustness and effectiveness of the proposed robust federated learning algorithm in edge-intelligent networks.

关键词： edge-intelligent network federated learning imperfect CSI robust design

Automatic Narrow-Deep Feature Recognition for Mould Manufacturing

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Computer science & Technology 2011年第3期26卷 528-537页

作者：陈正鸣何坤金刘景 college of Computer science and information engineering Hohai University

There usually exist narrow-long-deep areas in mould needed to be machined in special machining. To identify the narrow-deep areas automatically, an automatic narrow-deep feature （NF） recognition method is put forward accordingly. First, the narrow-deep feature is defined innovatively in this field and then feature hint is extracted from the mould by the characteristics of narrow-deep feature. Second, the elementary constituent faces （ECF） of a feature are found on the basis of the feature hint. By means of extending and clipping the ECF, the feature faces are obtained incrementally by geometric reasoning. As a result, basic narrow-deep features （BNF） related are combined heuristically. The proposed NF recognition method provides an intelligent connection between CAD and CAPP for machining narrow-deep areas in mould.

关键词： narrow-deep feature feature recognition face-pair mould

Quantum and classical correlations for a two-qubit X structure density matrix

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2011年第10期20卷 23-29页

作者：丁邦福王小云赵鹤平 college of Physical science and information engineering Jishou University

We derive explicit expressions for quantum discord and classical correlation for an X structure density matrix. Based on the characteristics of the expressions, the quantum discord and the classical correlation are easily obtained and compared under different initial conditions using a novel analytical method. We explain the relationships among quantum discord, classical correlation, and entanglement, and further find that the quantum discord is not always larger than the entanglement measured by concurrence in a general two-qubit X state. The new method, which is different from previous approaches, has certain guiding significance for analysing quantum discord and classical correlation of a two-qubit X state, such as a mixed state.

关键词： quantum and classical mutual information X structure density matrix quantum dis-cord classical correlation entanglement

Statistical CSI based design for intelligent reflecting surface assisted MISO systems

在线全文

学校读者我要写书评

暂无评论

science China(information sciences) 2020年第12期63卷 211-220页

作者： Xiaoling HU Junwei WANG Caijun ZHONG college of information science and Electronic engineering Zhejiang University

This paper considers an intelligent reflecting surface(IRS) aided multiple-input single-output communication system, where statistical channel state information(CSI) is exploited for transmit beamforming and IRS beamforming. A tight upper bound is derived for the ergodic capacity of the system. Based on which, the joint optimization of transmit beam and IRS beam are studied. Depending on whether a line-of-sight path exists between the access point and user, two different cases, namely, Rician fading and Rayleigh fading, are separately treated. Specifically, for the Rician fading case, an iterative algorithm is proposed, which is guaranteed to converge. For the Rayleigh fading case, closed-form designs are obtained for the transmit beam and IRS beam. Simulation results show the proposed beamforming scheme achieves similar performance as the benchmark algorithm requiring instantaneous CSI.

关键词： beamforming IRS MISO statistical CSI ergodic capacity