Construction of Low Delay Maximal Rate Single-Symbol Decodable Distributed STBC with Channel Phase Information

Exploiting the source-to-relay channel phase information at the relays can increase the rate upper-bound of distributed orthogonal space-time block codes(STBC)from 2/K to 1/2,where Kis the number of relays.This technique is known as distributed orthogonal space-time block codes with channel phase information(DOSTBC-CPI).However,the decoding delay of existing DOSTBC-CPIs is not optimal.Therefore,based on the rate of 1/2 balanced complex orthogonal design(COD),an algorithm is provided to construct a maximal rate DOSTBC-CPI with only half the decoding delay of existing DOSTBC-CPI.Simulation results show that the proposed method exhibits lower symbol error rate than the existing DOSTBC-CPIs.

Recent Progress of Full‑Field Three‑Dimensional Shape Measurement Based on Phase Information

Full-field three-dimensional(3D)measurement technology based on phase information has become an indispensable part of geometric dimension measurement in modern scientific research and engineering applications.This field has been developing and evolving for the study of highly reflective phenomena,diffuse reflections,and specular surfaces,and many novel methods have emerged to increase the speed of measurements,enhance data accuracy,and broaden the robustness of the system.Herein,we will discuss the latest research progress in full-field 3D shape measurement based on phase information systematically and comprehensively.First,the fundamentals of 3D shape measurement based on phase information are introduced,namely,phase-shifting and transform-based methods.Second,recent technological innovations are highlighted,including increases in measurement speed and automation and improvements in robustness in complex environments.In particular,the challenges faced by these technological advances in solving highly dynamic,composite surface measurement problems are presented,i.e.,with multiexposure techniques proposed for high dynamics that extend the dynamic range of the camera to reduce the effects of overexposure but increase the cost of time and have high hardware requirements,fringe adaptive techniques that overcome light variations but are computationally complex,and multipolarized camera techniques that reduce the effects of light variations but are sensitive to the light source.Third,the phase-shifting method combined with coding is proposed to improve the measurement speed,but the accuracy is slightly reduced.Deep learning techniques are proposed to cope with measurements in complex environments,but the dataset computation process is cumbersome.Finally,future research directions are suggested,and the challenges are presented.Overall,this work provides a reference for researchers and engineers.

税收信息化建设与企业税收负担:基于金税三期的准自然实验

基于金税三期政策试点推广所引起的准自然实验,利用2009—2018年A股上市企业数据,以带有调节效应的渐进双重差分模型考察了金税三期对企业税收负担的政策效应。结果表明,税收信息化建设能够显著降低企业税收负担,通过稳健性检验后结论依然成立。金税三期降低企业税负的效应还受到企业规模影响,企业规模越小,税收信息化带来的降低税负的政策效应更明显。该政策效应亦存在区域特征依赖性,在东部与中部地区政策效应显著,但西部与东北部地区并不显著。金税三期工程较好解决了税收信息化建设与降低企业税负之间的冲突,这一结论也有助于正确认识信息化建设与降低企业税收负担之间的关系。

Phase estimation of phase shifts in two arms for an SU(1,1)interferometer with coherent and squeezed vacuum states

We theoretically study the quantum Fisher information（QFI） of the SU（1,1） interferometer with phase shifts in two arms by coherent squeezed vacuum state input, and give the comparison with the result of phase shift only in one arm.Different from the traditional Mach–Zehnder interferometer, the QFI of single-arm case for an SU（1,1） interferometer can be slightly higher or lower than that of two-arm case, which depends on the intensities of the two arms of the interferometer.For coherent squeezed vacuum state input with a fixed mean photon number, the optimal sensitivity is achieved with a squeezed vacuum input in one mode and the vacuum input in the other.

Line spectrum detection algorithm based on the phase feature of target radiated noise

In order to improve the performance of line spectrum detection,according to the feature that the underwater target radiated noise containing stable line spectrum,the differences of the phase difference between line spectrum and background noise,a weighted line spectrum detection algorithm based on the phase variance is proposed in frequency domain.After phase difference alignment,the phase variance of line spectrum and the phase of background noise,respectively,are small and big in frequency domain,this method utilizes the weighted statistical algorithm to cumulate the frequency spectrum based on the phase variance,which can restrain the background noise disturbance,and enhance the signal to noise ratio（SNR）.The theory analysis and experimental results both verify that the proposed method can well enhance the energy of line spectrum,restrain the energy of background noise,and have better detection performance under lower SNR.

企业信息化集成模式研究

企业信息化是分阶段进行的,每个阶段选取不同的业务环节,进行不同集成方式的信息化,并需要根据信息化条件的成熟情况适时更新集成方式。详细分析了单项业务级、部门级以及企业级集成方式的特点、内容等,并分析了这三种集成方式的差异。

教育信息化的美国之路——基于四次国家教育技术计划的考察

在美国教育信息化建设过程中,四次国家教育技术计划起到了举足轻重的作用。文章首先从计划提出的背景、当时对教育技术的理解以及提出的建设目标或解决方案等方面分析了美国迄今为止的四个国家教育技术计划,并从中归纳出美国教育信息化的一些特点及其对我国教育信息化建设的启示。

Characteristic of femtosecond laser-pulsed digital holography

Digital holography can be applied to ultrafast detection when a femtosecond laser pulse is used. In this paper, the interference process of two femtosecond laser pulses is studied and the recording process of the femtosecond laser pulsed digital hologram is simulated. Holograms at different recording angles are generated by integrating the instantaneous interference field. By analyzing the distribution of the reconstructed phase error, the characteristics of femtosecond laser pulsed digital holography are discussed.

Improved iterative convergence method in Q-ary LDPC coded high order PR-CPM

The Q-ary low-density parity-check（LDPC） coded high order partial response continuous phase modulation（PR-CPM） with double iterative loops is investigated. This scheme shows significant improvements in power and bandwidth efficiency, but at the expense of long iterative decoding delay and computational complexity induced by the improper match between the demodulator and the decoder. To address this issue, the convergence behavior of Q-ary LDPC coded CPM is investigated for the Q=2 and Q〉2 cases, and an optimized design method based on the extrinsic information transfer chart is proposed to improve the systematic iterative efficiency. Simulation results demonstrate that the proposed method can achieve a perfect tradeoff between iterative decoding delay and bit error rate performance to satisfy real-time applications.

基于建筑信息化的施工阶段工程安全管理研究

随着近些年来的社会进步和科技发展。各行各业在发展过程当中都取得了不错的成效。在建筑行业领域同样如此,在建筑行业的发展过程当中,工程管理趋于现代化和信息化发展模式可谓建筑行业的中流砥柱。有关部门以及相关工作人员要从建筑工程实际情况出发,选择科学的安全与质量控制方法,尽可能减少施工安全隐患,以及影响工程施工质量的各种因素,从整体上为建筑工程安全与质量保障提供支持。

Machine learning assisted prediction of dielectric temperature spectrum of ferroelectrics

In material science and engineering,obtaining a spectrum from a measurement is often time-consuming and its accurate prediction using data mining can also be difficult.In this work,we propose a machine learning strategy based on a deep neural network model to accurately predict the dielectric temperature spectrum for a typical multi-component ferroelectric system,i.e.,(Ba_(1−x−y)Ca_(x)Sr_(y))(Ti_(1−u−v−w)Zr_(u)Sn_(v)Hf_(w))O_(3).The deep neural network model uses physical features as inputs and directly outputs the full spectrum,in addition to yielding the octahedral factor,Matyonov–Batsanov electronegativity,ratio of valence electron to nuclear charge,and core electron distance(Schubert)as four key descriptors.Owing to the physically meaningful features,our model exhibits better performance and generalization ability in the broader composition space of BaTiO3-based solid solutions.And the prediction accuracy is superior to traditional machine learning models that predict dielectric permittivity values at each temperature.Furthermore,the transition temperature and the degree of dispersion of the ferroelectric phase transition are easily extracted from the predicted spectra to provide richer physical information.The prediction is also experimentally validated by typical samples of(Ba_(0.85)Ca_(0.15))(Ti_(0.98–x)Zr_(x)Hf_(0.02))O_(3).This work provides insights for accelerating spectra predictions and extracting ferroelectric phase transition information.

税收信息化建设对企业纳税遵从度的影响研究

本文以2009~2016年我国上市公司为样本,利用金税三期工程在不同省份逐步推进所引起的"自然实验",分析了税收信息化建设对企业偷逃税决策的影响。研究发现,以金税三期工程上线为代表的税收信息化建设能够显著地提升企业纳税遵从度,并且试点越早的省份,企业纳税遵从度的提高越显著。特别地,在剔除了营改增对企业偷逃税行为的影响后并不影响本文的结论。本文的研究为评估税收信息化建设的效果以及进一步完善税收征管提供了增量的经验证据。