waves

摘要： The solar wind protons undergo significant perpendicular heating when they propagate in the interplanetary space.Stochastic heating and cyclotron resonance heating due to kinetic Alfvén waves(KAWs) are two proposed mechanisms. Which mechanism accounts for the perpendicular heating is still an open question. This paper performs tests for the two mechanisms based on Wind observations during 2004 June and 2019 May. Results show that heating rates in terms of stochastic heating theory considerably depend on the parameter of plasma β. For the solar wind with moderately high β, the theoretical heating rates are comparable to or larger than empirical heating rates, suggesting that the stochastic heating could be a powerful mechanism. For the solar wind with low β, on the contrary, the majority of data have theoretical heating rates much lower than empirical heating rates, showing that the stochastic heating seems to be weak in this case. On the other hand, it is found that, when the propagation angles of KAWs are around 70°, theoretically predicted damping wavenumbers of KAWs are equal to the observed wavenumbers at which magnetic energy spectra become significantly steep. This may imply that resonance heating due to cyclotron damping of KAWs could be another mechanism if KAWs have propagation angles around 70°.

摘要： Observations of solar wind plasma find that the drift velocity between alpha beams and protons,vα,is reduced with the heliocentric distance,but the ratio of vαto vA(the local Alfven velocity)does not vary obviously and has a typical velocity ratio of vα/vA≤1.The alpha beam instability is believed to be responsible for the deceleration of alpha beams in the solar wind.However,the role of the temperature anisotropy of ions(protons and alpha particles)on the alpha beam instability has not been examined.Based on the kinetic theory of the PDRK solver,this study systemically investigates the alpha beam instability in the presence of proton and alpha temperature anisotropies and considers the effects of these temperature anisotropies on the instability at an arbitrary propagation angle relative to the ambient magnetic field.It is found that the real frequencies,growth rates and threshold conditions of the excited waves sensitively depend on the proton temperature anisotropy T_(i⊥)/T_(i‖)and the alpha temperature anisotropy T_(α⊥)/T_(α‖),as well as the parallel electron betaβe‖.In particular,for both alpha beam and proton temperature anisotropy driven cases,the parallel magnetosonic/whistler(PM/W),backward magnetosonic/whistler(BM/W)and oblique Alfvén/ion cyclotron(OA/IC)waves arise when T_(i⊥)/T_(i‖)1.The presence of anisotropic protons leads to a lower velocity threshold for the OA/IC and BM/W waves at T_(i⊥)/T_(i‖)1.For both alpha beam and alpha temperature anisotropy driven cases,the PM/W and OA/IC waves are unstable when T_(α⊥)/T_(α‖)1.The presence of anisotropic alpha particles results in a lower threshold velocity for the PM/W wave at T_(α⊥)/T_(α‖)1.On account of the influences of the anisotropic proton and alpha,these alpha beam instabilities can effectively constrain the alpha-beam drift velocity to less than or equal to the local Alfven velocity.These results may shed light on the evolution and deceleration mechanism of alpha particles in the solar wind.

摘要： In many areas around the world, wake surfing has been cited as one of the major causes of lakeshore erosion and turbidity. This paper quantifies the impact related to turbidity and erosion with the use of computational fluid dynamics (CFD) of boat wakes in shallow water and the build-up of wind driven waves. The energy, type and direction of the boat’s wake are described quantitatively and a table for predicting wind driven waves over varying fetches, depth and wind speeds is provided. The CFD simulation shows that if a wake surf boat is operated 200 ft from shore and in at least 10 ft of water, the environmental impact is minimal.

摘要： Recent investigations have derived the relation between the near-field plane amplitude and the surface deformation of reflector antenna,namely deformation-amplitude equation(DAE),which could be used as a mathematical foundation of antenna surface measurement if an effective numerical algorithm is employed.Traditional algorithms are hard to work directly due to the complex mathematical model.This paper presents a local approximation algorithm based on artificial neural network to solve DAE.The length factor method is used to construct a trial solution for the deformation,which ensures the final solution always satisfies the boundary conditions.To improve the algorithm efficiency,Adam optimizer is employed to train the network parameters.Combining the application of the data normalization method proposed in this paper and a step-based learning rate,a further optimized loss function could be converged quickly.The algorithm proposed in this paper could effectively solve partial differential equations without boundary conditions such as DAE,which at the same time contains the first-order and the second-order partial derivatives,and constant terms.Simulation results show that compared with the original algorithm by Fast Fourier transform,this algorithm is more stable and accurate,which is significant for the antenna measurement method based on DAE.

摘要： In this paper, the modifications of the whistler dispersion characteristics are investigated which arise if resonant electrons are taken into account. The following chain of processes is emphasized: Generation of whistler waves propagating at different angles to the magnetic field and their nonlinear interaction with resonant electrons result in the appearance of modulated electron beams in the background plasma. As a result, the dispersion characteristics of waves in this new plasma might be significantly changed. By analysing the modified dispersion characteristics these changes are discussed. Supported by particle simulations and space observations, it is assumed that in the electron distribution function at the resonance velocity a plateau-like beam is formed. Because of the weakness of the beam, the term “beam/plateau population (b/p)” is used. By solving the kinetic dispersion relation of whistler waves in electron plasmas with b/p populations, the associated modifications of the whistler dispersion characteristics are presented in diagrams showing, in particular, the frequency versus propagation angle dependence of the excited waves. It is important to point out the two functions of the b/p populations. Because of the bi-directional excitation of whistler waves by temperature anisotropy, one has to distinguish between up- and downstream populations and accordingly between two b/p modes. The interaction of the beam-shifted cyclotron mode ω= Ωe + k⋅Vb (V bVb is the b/p velocity, Ωe: electron cyclotron frequency) with the whistler mode leads to enhanced damping at the ω-k point where they intersect. This is the origin of the frequency gap at half the electron cyclotron frequency (ω~Ωe/2) for quasi-parallel waves which are driven by temperature anisotropy. Furthermore, it is shown that the upstream b/p electrons alone (in the absence of temperature anisotropy) can excite (very) oblique whistler waves near the resonance cone. The governing instability results from the interaction of the beam/plateau mode ω= k⋅Vb (Vb > 0) with the whistler mode. As a further remarkable effect, another frequency gap at ω~Ωe/2 in the range of large propagation angles may arise. It happens at the triple point where both b/p modes and the whistler mode intersect. Our investigation shows that the consideration of resonant electrons in form of beam/plateau populations leads to significant modifications of the spectrum of magnetospheric whistler waves which are originally driven by temperature anisotropy. Relations to recent and former space observations are discussed.

摘要： Kink oscillations of coronal loops are often influenced by external events and this results in various changes of the oscillations.Studying the changes can provide valuable information for understanding kink oscillations.Our observation focuses on a flare region acquired by the Atmospheric Imaging Assembly on the Solar Dynamics Observatory spacecraft on 2016 March 23.There are a bunch of arched loops and an open loop near the region.However,their oscillations show very low amplitudes.So we used the jerk-aware motion method to magnify the weak oscillations.We found that before the flare onset at 02:59 UT,there were some large loops above the arched loops being raised rapidly.The properties of the weak oscillations show clear changes.On the one hand,the oscillations in the arched loops were decayless initially,but both their amplitude and period increased after 02:30 UT and before the flare onset.Once enhanced,the oscillations decayed with time.On the other hand,the oscillations in the open loop were nearly constant before and after 02:30 UT,but their period increased.This means that the changes in periods and amplitudes of oscillations are likely associated with the loops raised before the flare.

摘要： 本文以全景声为核心内容,阐述全景声的诞生历史、技术原理、技术发展以及实际应用。通过图文的形式更加直观的阐述观点和问题,并结合实际加以求真论证。作者希望通过本篇论文帮助大家认识了解全景声的技术和应用。

摘要： “后浪”一词来自中国非常有名的一句谚语:“长江后浪推前浪,一代更比一代强。”中国知名视频软件B站发布的一支名为《后浪》的视频,令这一词语在当代迅速走红,并引发了人们强烈的共鸣。“后浪”是用隐喻的手法来表示“年轻一代”,英文中我们可以用rising waves来表示,rising正能体现“后浪”这一词中蕴含的对年轻的人们的期许和希冀,即无畏拼搏、不甘沉沦。

摘要： This paper presents a new method to obtain the deformation distribution on the main reflector of an antenna only by measuring the electric intensity on a spherical surface with the focal point as the center of the sphere,regardless of phase.Combining the differential geometry theory with geometric optics method,this paper has derived a deformation-intensity equation to relate the surface deformation to the intensity distribution of a spherical near-field directly.Based on the finite difference method(FDM)and GaussSeidel iteration,deformation has been calculated from intensity simulated by geometrical optics(GO)and physical optics(PO)methods,respectively,with relatively small errors,which prove the effectiveness of the equation proposed in this paper.By means of this method,it is possible to measure the deformation only by scanning the electric intensity of a single hemispherical near-field whose area is only about 1/15 of the aperture.The measurement only needs a plane wave at any frequency as the incident wave,which means that both the signals from the outer space satellite and the far-field artificial beacon could be used as the sources.The scanning can be realized no matter what attitude and elevation angle the antenna is in because the size and angle of the hemisphere are changeable.

摘要： In-situ observations from the FREJA magnetospheric research satellite and the Fast Auroral SnapshoT satellite have shown that plasma waves are frequently observed in the auroral plasma,which are believed to be fundamentally important in wave energy dissipation and particle energization.However,the effects of a displacement current on these waves have not been examined.Based on the two-fluid theory,we investigate the dispersion relation and polarization properties of fast,Alfven,and slow modes in the presence of a displacement current,and the effects of the displacement current on these waves are also considered.The results show that the wave frequency,polarization,magnetic helicity and other properties for the fast and Alfven modes are highly sensitive to the normalized Alfven velocity v_(A)/c,plasma beta β,and propagation angle θ,while for the slow mode the dependence is minor.In particular,for both fast and Alfven modes,the magnetic helicity is obviously different with and without the displacement current,especially for the Alfven mode with the helicity reversals from right-handed to left-handed when v_(A)/c increases from 0 to 0.3.The charge-neutral condition of both fast and Alfven modes with frequencies larger than the proton cyclotron frequency is invalid in the presence of the displacement current.Moreover,the presence of the displacement current leads to relatively large magnetic compressibility for the Alfven mode and relatively large electron compressibility for the fast mode.These results can be useful for a comprehensive understanding of the wave properties and the physics of particle energization phenomena in auroral plasmas.

摘要： 本发明属于计算机科学领域，尤其涉及一种针对Z‑Wave智能设备识别的方法，包括构建Z‑Wave网络环境，采集Z‑Wave智能设备无线通信数据，并根据样本特征值构建特征矩阵；使用字典特征提取和PCA降维对样本特征矩阵进行处理，得到基于数值的特征矩阵；输入特征矩阵和设备标签，经过BP神经网络进行训练，得到对应参数学习率、连接权、阈值，并获取样本的实际输出值；BP神经网络的输出层后连接有相似层，并在相似层计算测试样本实际输出值与设备标签的相似度；根据已知设备的测试样本和未知设备的测试样本相似度，确定界值，并根据界值判断待识别的设备为已知设备还是未知设备；本发明能够识别设备是否为已知设备，帮助Z‑Wave智能设备的生产者更有效的实现入侵检测，能够帮助使用者规避被恶意设备接入攻击的危险。

摘要： 本发明公开了一种基于DSRC/WAVE的车联网中的安全消息合作传输方法，该方法的步骤包括：首先，每个车辆在控制信道时隙期间均收集其一跳范围内的邻居节点在该控制信道时隙期间的下一个服务信道时隙期间将工作的信道号，收集到的服务信道号构成服务信道集合；其次，若某一车辆在该控制信道时隙期间的下一个服务信道时隙期间生成时间安全消息，则该车辆调谐到控制信道上广播安全消息，并在其一跳范围内的邻居节点中寻找在该控制信道时隙期间的下一个服务信道时隙期间仍保留在控制信道上的车辆进行合作传输。本发明是一种新的安全消息合作传输方案进一步提高传输效率，要让安全消息在尽可能短的时间内传输给更多的车辆。

摘要： 本发明涉及磁共振成像的技术领域，公开了一种Wave‑CAIPI磁共振成像参数的解析优化方法、装置及介质，所述参数优化方法对成像序列参数的相对幅度a和周期c做自动优化，其中，所述参数相对幅度a和周期c的优化算法使用梯度下降法更新正弦梯度场的相对幅度a和周期c。本发明从理论和仿真两方面分析了Wave‑CAIPI磁共振的成像序列参数(相对幅度a和周期c)对几何因子g‑factor的影响，对现有技术中的Wave‑CAIPI磁共振成像技术做了参数优化，优化后的参数(相对幅度a和周期c)相比经验选择的参数(相对幅度a和周期c)，能够达到更小的几何因子g‑factor，从而获得信噪比更高的重建图像。

摘要： 本发明提供一种基于Z_Wave的智能家居装置，涉及智能家居技术领域，以解决现有的智能家居中的智能插排在使用的时候，插排导线过长容易绊倒行走的人员的问题，包括主体，所述主体的内部安装有Z_Wave模块，且主体的内部安装有电机以及推动杆，电机的侧端安装有齿轮，并且主体的内部安装有清理机构；清理机构，所述清理机构内的内腔设在主体的底端内部，且内腔的顶部与顶槽的底部相连接，并且托板的顶部在载板的底部滑动；收卷机构，所述收卷机构安装在主体的底部，且收卷机构内的底板通过转轴安装在主体的底部。使插排导线缠绕在支架的外侧，对过长的插排导线进行整理，使导线处于比较合适的使用长度，防止过长的插排导线绊倒行走的人员。

摘要： 本发明属于计算机科学领域，尤其涉及一种针对Z‑Wave智能设备识别的方法，包括构建Z‑Wave网络环境，采集Z‑Wave智能设备无线通信数据，并根据样本特征值构建特征矩阵；使用字典特征提取和PCA降维对样本特征矩阵进行处理，得到基于数值的特征矩阵；输入特征矩阵和设备标签，经过BP神经网络进行训练，得到对应参数学习率、连接权、阈值，并获取样本的实际输出值；BP神经网络的输出层后连接有相似层，并在相似层计算测试样本实际输出值与设备标签的相似度；根据已知设备的测试样本和未知设备的测试样本相似度，确定界值，并根据界值判断待识别的设备为已知设备还是未知设备；本发明能够识别设备是否为已知设备，帮助Z‑Wave智能设备的生产者更有效的实现入侵检测，能够帮助使用者规避被恶意设备接入攻击的危险。

摘要： 本实用新型涉及生物反应器技术领域，公开了一种新型wave高效生物反应器，包括摇动平台和控制装置，所述摇动平台的顶部连接有盖板，所述摇动平台的底部两端固定设有上支座，所述控制装置的顶部焊接有底板，所述底板的顶部两端固定设有下支座，所述下支座与上支座之间贯穿连接有横杆，所述摇动平台的底部前端固定设有定位块，所述定位块的底部连接有连接杆，所述连接杆的底部侧端经过连接轴连接有支撑杆，所述支撑杆的端部经过驱动轴连接有驱动电机，所述驱动电机的顶部通过安装板安装于底板的底部。该新型wave高效生物反应器，高效的将细胞培养袋放置于摇动平台内部晃动，使得培养液中产生波浪，从而充分混合培养物进行高效传氧反应，安全实用。

摘要： 本实用新型公开了一种wave生物反应器的减震底座,包括wave生物反应器本体和支撑架，所述支撑架的底部设置有底座，所述底座的内部与支撑架的底部之间设置有减震装置，所述减震装置包括两个对称分布的固定框和固定板，所述固定框的内部等间距设置有若干第一弹簧，所述固定板的顶部对称设置有两组第一连接柱，所述固定板的顶部中间设置有第二连接柱，所述固定板的底部中间横向对称设置有两个第二弹簧，所述第二弹簧的两端与固定板的底部之间均设置有连接板，所述固定板的两端对称设置有两个活动杆，所述活动杆之间设置有配合第一弹簧使用的限位板。本实用新型通过减震装置，可以有效的降低设备运行时产生得分震动，提高了反应的成功率。

摘要： 本实用新型公开了一种基于Z‑Wave无线控制的LED照明设备，涉及LED照明设备技术领域。包括照明灯和灯罩，所述照明灯上设置有Z‑Wave无线控制芯片，所述灯罩的顶部设置有进出气组件，所述照明灯的顶部设置有从动控制组件，所述进出气组件包括管道，所述管道的底部与灯罩连通，所述管道与圆块活塞连接。通过设置的进出气组件，当照明灯开始工作时，灯罩受照明灯的影响温度逐渐升高，灯罩内部的气体受热膨胀，此时灯罩顶部左侧的管道只能进气，灯罩顶部右侧的管道只能出气，在气压影响下，灯罩内部的气体从灯罩右侧顶部的管道跑出，实现对灯罩内部进行换气，可以有效的降低灯罩和照明灯的温度，同时也避免了照明灯与Z‑Wave无线控制芯片直接接触的问题。

摘要： 本实用新型提供一种Zigbee和Z‑wave共用单天线的智能家居网关，其包括主芯片以及均与所述主芯片连接的TYPE‑C供电接口和以太网，还包括Zigbee无线模块、Z‑wave无线模块、均与所述Zigbee无线模块和Z‑wave无线模块连接的同向双工器以及天线；其中所述主芯片通过分别与所述Zigbee无线模块和Z‑wave无线模块连接；所述同向双工器内设有至少一个阻抗匹配电路以及与该阻抗匹配电路连接的公共端；所述天线与所述公共端连接。本实用新型Zigbee和Z‑wave智能家居网关，采用Zigbee和Z‑wave两种不同工作频率的无线通信协议共用单天线的技术，既能同时连接这两种无线通信协议的智能家居设备，又降低了产品的设计难度，减小了产品的体积。

摘要： 本实用新型公开了一种基于Z‑Wave无线通信的智能窗帘控制系统，包括微处理器、手动按钮、无线通信模块、交流电机驱动电路、交流电机和交流电机驱动电流与电压采集电路，手动按钮与无线通信模块的输出端均与微处理器的输入端电性连接，本实用新型所达到的有益效果是：本实用新型通过设置交流电机驱动电路配合微处理器，能够控制窗帘打开指定的百份比和关闭指定的百份比，同时通过设置交流电机驱动电流与电压采集电路，能够实时采集交流电机的功率，并配合基于Z‑Wave协议的无线通信模块实现远程监控窗帘交流电机的能耗，同时对交流电机的运行状态进行实时监控，可以进行过流保护，防止交流电机因堵转而烧坏，从而使得窗帘具有更好的使用效果。