Transfer characteristics of dynamic biochemical signals in non-reversing pulsatile flows in a shallow Y-shaped microfluidic channel: signal filtering and nonlinear amplitude-frequency modulation

The transports of the dynamic biochemical signals in the non-reversing pulsatile flows in the mixing microchannel of a Y-shaped microfluidic device are ana- lyzed. The results show that the mixing micro-channel acts as a low-pass filter, and the biochemical signals are nonlinearly modulated by the pulsatile flows, which depend on the biochemical signal frequency, the flow signal frequency, and the biochemical signal transporting distance. It is concluded that, the transfer characteristics of the dynamic biochemical signals, which are transported in the time-varying flows, should be carefully considered for better loading biochemical signals on the cells cultured on the bottom of the microfluidic channel.

A 532 nm molecular iodine optical frequency standard based on modulation transfer spectroscopy

We report construction of an iodine-stabilized laser frequency standard at 532 nm based on modulation transfer spectroscopy(MTS)technology with good reproducibility.A frequency stability of 2.5×10^(-14)at 1 s averaging time is achieved,and the frequency reproducibility has a relative uncertainty of 3.5×10^(-13),demonstrating the great stability of our setup.The systematic uncertainty of the iodine-stabilized laser frequency standard is evaluated,especially the contribution of the residual amplitude modulation(RAM).The contribution of the RAM in MTS cannot be evaluated directly.To solve this problem,we theoretically deduce the MTS signal with RAM under large modulation depth,and prove that the non-symmetric shape of the MTS signal is directly related to the MTS effect.The non-symmetric shape factor can be calibrated with a frequency comb,and in real experiments,this value can be obtained by least-squares fitting of the MTS signal,from which we can infer the RAMinduced frequency shift.The full frequency uncertainty is evaluated to be 5.3 kHz(corresponding to a relative frequency uncertainty of 9.4×10^(-12)).The corrected transition frequency has a difference from the BIPM-recommended value of 2 kHz,which is within 1σ uncertainty,proving the validity of our evaluation.

Effect of Hot Carrier on Amplitude Modulation and Demodulation of Gaussian High Power Helicon Wave in Homogeneous Longitudinally Magnetized Strain Dependent Dielectric Material

In the present communication, the hydrodynamic model is used to investigate the amplitude modulation as well as demodulation of an electromagnetic wave of high power helicon pump wave into another helicon wave in strain dependent dielectric material incorporating carrier heating (CH) effects. The consideration of CH in modulation and demodulation is prime importance for the adding of new dimension in analysis of amplification of acoustic helicon wave. By using the dispersion relation, threshold pump electric filed and growth rate of unstable mode from the modulation and demodulation of the high power helicon wave well above from the threshold value will be discussed in the present analysis. The numerical analysis is applied to a strain dependent dielectric material, BaTiO3 at room temperature and irradiated with high power helicon wave of frequency 1.78 × 1014 Hz. This material is very sensitive to the pump intensities, therefore during studies, Gaussian shape of the helicon pump wave is considered during the propagation in stain dependent dielectric material and opto-acoustic wave in the form of Gaussian profile (ω0,κ0) is induced longitudinally along the crystallographic plane of BaTiO3. Its variation is caused by the available magnetic field (ωc), interaction length (z) and pulsed duration of interaction (τ). From the analysis of numerical results, the incorporation of CH effect can effectively modify the magnitude of modulation or demodulation of the amplitude of high power helicon laser wave through diffusion process. Not only the amplitude modulation and demodulation of the wave, the diffusion of the CH effectively modifies the growth rate of unstable mode of frequency in BaTiO3. The propagation of the threshold electric field shows the sinusoidal or complete Gaussian profile, whereas this profile is found to be completely lost in growth of unstable mode. It has also been seen that the growth rate is observed to be of the order of 108 - 1010 s-1 but from diffusion of carrier heating, and that its order is enhanced from 1010 - 1012 s-1 with the variation of the magnetized frequency from 1 to 2.5 × 1014 Hz.

Comparison of performance between bipolar and unipolar double-frequency sinusoidal pulse width modulation in a digitally controlled H-bridge inverter system

By deriving the discrete-time models of a digitally controlled H-bridge inverter system modulated by bipolar sinu- soidal pulse width modulation （BSPWM） and unipolar double-frequency sinusoidal pulse width modulation （UDFSPWM） respectively, the performances of the two modulation strategies are analyzed in detail. The circuit parameters, used in this paper, are fixed. When the systems, modulated by BSPWM and UDFSPWM, have the same switching frequency, the stabil- ity boundaries of the two systems are the same. However, when the equivalent switching frequencies of the two systems are the same, the BSPWM modulated system is more stable than the UDFSPWM modulated system. In addition, a convenient method of establishing the discrete-time model of piecewise smooth system is presented. Finally, the analytical results are confirmed by circuit simulations and experimental measurements.

Targeted treatment of cancer with radiofrequency electromagnetic fields amplitude-modulated at tumor-specific frequencies

In the past century, there have been many attempts to treat cancer with low levels of electric and magnetic fields. We have developed noninvasive biofeedback examination devices and techniques and discovered that patients with the same tumor type exhibit biofeedback responses to the same, precise frequencies. Intrabuccal administration of 27.12 MHz radiofrequency(RF) electromagnetic fields(EMF), which are amplitude-modulated at tumor-specific frequencies, results in long-term objective responses in patients with cancer and is not associated with any significant adverse effects. Intrabuccal administration allows for therapeutic delivery of very low and safe levels of EMF throughout the body as exemplified by responses observed in the femur, liver, adrenal glands, and lungs. In vitro studies have demonstrated that tumor-specific frequencies identified in patients with various forms of cancer are capable of blocking the growth of tumor cells in a tissue- and tumor-specific fashion. Current experimental evidence suggests that tumor-specific modulation frequencies regulate the expression of genes involved in migration and invasion and disrupt the mitotic spindle. This novel targeted treatment approach is emerging as an appealing therapeutic option for patients with advanced cancer given its excellent tolerability. Dissection of the molecular mechanisms accounting for the anti-cancer effects of tumor-specific modulation frequencies is likely to lead to the discovery of novel pathways in cancer.

Time-Fractal Modulation—Possible Modulation Effects in Human Therapy

The malignant processes deviate from the healthy homeostatic control, and various “tricks” enable malignant cells to avoid the healthy regulation. Consequently, the malignant structures miss the apoptosis and proliferate without restriction, and without the formation of communication networks in the newly formed cells. The modulation supports the homeostatic control to rearrange the health regulation processes in various ways. The modulation acts with stochastic processes, using stochastic resonances for molecular excitations, supporting the regulative enzymatic processes. The number of stochastic resonant frequencies is as many as the number of enzymatic reactions. The malignant cells differ structurally and dynamically in their connections and interactions from their healthy host tissues. The radiofrequency carrier is modulated with an appropriate time-fractal (1/f) noise to select the autonomic cancer-cells, destroy them, or force the precancerous, semi-individual cells to participate in the networking connections. The modulation in this way limits the cellular autonomy of malignant cells and boosts the healthy control. The resonant energy triggers apoptotic processes and helps immunogenic actions deliver extracellular genetic information for antigen-presentation. The modulation is applied in clinical practice. The therapy (modulated electro-hyperthermia, mEHT) is intensively used in oncology in complementary applications and for palliative stages, and occasionally even as a monotherapy.

Optimized analysis of ionospheric amplitude modulated heating parameters for excitation of very/extremely low frequency radiations

It is now well known that amplitude modulated(AM) high frequency(HF) radio wave transmissions into the ionosphere can be used to generate very/extremely low frequency(VLF/ELF) radio waves using the so-called ‘electrojet antenna’. Duty cycle and heating frequency are analyzed and discussed with the lower-ionosphere modulated heating model, so as to improve the radiation efficiency of VLF/ELF waves in AM ionospheric heating experiments. Based on numerical simulation, the ranges of parametric selectivity in optimal duty cycle and heating frequency( fHF) are derived. The International Reference Ionosphere 2015(IRI-2015) model and two-parameter model are used to predict background electron density profiles, and optimized ranges of duty cycle for different density profiles are analyzed and compared. The influences of wave polarizations on optimal duty cycle are also discussed. It is shown that intensity of the VLF/ELF equivalent radiation source(M) firstly rises and then falls with the increase of duty cycle. When using the IRI model, M peaks at a duty cycle of 50%, optimally ranging from 40%-70%. For the two-parameter model case, an optimal duty cycle is 40% and the optimized ranges vary from 30%-60%. Heating with an X-mode polarization is more efficient than with the O-mode case in VLF/ELF wave generation. Nevertheless, an optimal duty cycle is almost independent of HF wave polarizations. To obtain better VLF/ELF generation, optional fHFmay be 0.8-0.9 times of foE for the O-mode heating and 0.75-0.85 times for the X-mode polarization case. Finally, the variations of these two parameters in different latitudes are discussed.

基于时频域分析的车载毫米波雷达干扰抑制方法

文中针对车载调频连续波雷达之间相互干扰导致虚警和漏警的问题,提出一种在时频域基于改进经验模式分解和自回归模型相结合的干扰抑制方法。该方法首先使用经验模式分解区分出拍频信号中干扰分量主导的低阶本征模态函数,将其转换到短时傅里叶变换域后通过全局阈值方法进行干扰分量定位;其次,在时频域根据定位信息将拍频信号包含干扰的数据置零;最后,使用自回归模型对拍频信号中缺失的有用信号进行估计并插值。通过仿真和实测结果显示,该方法在精确地去除干扰分量的同时可以减少有用信号的功率损失,干扰抑制后的信号与参考信号的相关系数达到0.9697。与现有干扰抑制技术相比文中方法也体现出更优的干扰抑制性能。

基于单片机的直流电机变频调速方法与仿真

针对电机谐波损耗及逆变器输出谐波信号影响直流电机变频调速的稳定性,导致调速性能不佳等,提出一种基于单片机的直流电机变频调速方法。建立直流电机变频调速状态空间模型,通过上述模型获取变频调速系统的运行状态;采用电流、速度双闭环PI控制器实现直流电机的变频调速初步控制,使直流电机变频调速系统可同时满足静态性能与动态性能;将直流侧电压输入至SVPWM脉宽调制系统,进一步降低电机谐波损耗和脉动转矩,实现变频调速的精确控制。仿真结果表明,所提方法的直流电机变频调速稳定性更佳、精度更高,整体效果更佳。

MEMS陀螺工作原理及其性能提升方法

MEMS陀螺是一种应用广泛的新型微惯性传感器,可实现高精度、小体积、抗干扰性强的角速度测量,被广泛应用于航空航天、平台钻井、自动驾驶、可穿戴设备以及手机中。近年来,随着对MEMS陀螺研究的不断深入,许多新型MEMS陀螺的工作原理被提出,由于测量原理的不同,其性能差异往往很大。本文旨在解决对MEMS陀螺的工作模式缺少系统性综述的问题,根据陀螺最终的读出技术,将MEMS陀螺的工作模式分为调幅、全角以及调频模式。在系统介绍其工作原理的基础上,详细讨论了各种工作模式下MEMS陀螺的性能提升方法。最后还介绍了各类MEMS陀螺的发展趋势,并结合各模式特性对MEMS陀螺的发展做出了展望。

基于一致性算法的柔性负荷参与调频方法研究

为提高可再生能源消纳能力,提出利用柔性负荷平衡功率缺额进行频率调节的方法。在新能源发电功率、日刚需负荷的多时间尺度预测结果基础上制订火力发电厂的出力计划与调度计划,随着时间尺度越接近,预测结果越精确,功率缺额越小,因此可采用一致性算法实时优化柔性负荷进行调频。首先建立调度层、负荷代理协调层及响应层3层调频控制架构,通过分布式负荷代理协调柔性负荷的需求响应。然后建立储能型柔性负荷、开关型柔性负荷的调度成本模型。最后以增量成本为一致性变量,调度成本最小为目标函数,进行分布式负荷代理的功率分配。仿真结果表明,该方法可实现在各负荷代理间进行功率缺额分配,并实现调度成本最低。

可再生能源配额制下风光储联合参与现货市场的交易决策

可再生能源配额制与现货市场建设的并行推进引起风电发电商、光伏发电商及储能电站(风光储)联合参与现货市场的交易决策发生变化。通过构建双层交易决策模型,对可再生能源配额制下风光储联合参与日前电能量及调频辅助服务市场的交易决策进行求解分析。模型上层以风光储总利润最大化为目标,同时考虑到风光储的内部调控,求解风光储最优交易策略;下层实现日前电能量和调频辅助服务市场的联合出清及绿色证书市场的清算。通过库恩-塔克(Karush-Kuhn-Tucker,KKT)条件、强对偶定理等方法将双层模型转换为混合整数线性规划问题进行求解。最后,通过算例验证了所提模型的有效性。结果表明:所提框架与模型能够优化风光储报量报价决策;可再生能源配额制的引入丰富了风光储的套利手段,风光储内部调控更加活跃;风光渗透率及配额制考核权重的变化对风光储的交易决策有重要影响。

基于锁模光学频率梳的高速数据传输

大数据时代网络数据流量的爆炸式增长给通信系统的容量和数据传输速率带来极大的挑战.本文基于锁模光学频率梳的宽光谱范围和高相位相干性提出了一种高频正交幅度调制信号生成方法,通过电光调制器对光学频率梳进行幅度相位整形并下变频至射频域,生成携带编码信息的高速、高阶、低相位噪声的调制信号,再结合锁模光学频率梳窄线宽、多波长的特性,仅使用单个激光器即可实现基于波分复用技术的大规模并行高速通信.仿真验证了该方案的可行性,随后在100 m的自由空间光链路中使用光子微波信号进行16元正交幅度调制通信实验,实现了误码率低于10^(–6)的14 Gbit/s数据传输.

风电齿轮箱振动信号耦合调制建模与应用

风电齿轮箱不同轮系间存在的耦合调制现象干扰了实际故障诊断,为此,针对两级行星一级平行结构的齿轮箱提出一种考虑级间耦合调制的现象学模型。首先,在风电齿轮箱振动信号幅值、频率解调分析基础上,定义了多级传动下的级间串联调制特性,并提出幅值-频率级间串联调制模型;通过构造多级调幅信号和调频信号,在频谱和解调谱中对串联调制特性进行仿真分析,并提出耦合调制特性边带能量指标用于模型评价;设计了与现场齿轮箱具有相同结构的缩比齿轮箱实验台,并在正常与故障状态下进行实验、现场联合分析,验证级间串联调制模型的有效性。结果表明:频率耦合调制现象在四种状态下尤为明显,其耦合调制特性边带能量分别为1.02、1.04、1.18、1.25。本模型所反映的齿轮箱级间耦合调制现象是齿轮箱本身所有,不会因齿轮箱的状态而发生改变,本模型为提高风电齿轮箱故障诊断准确性提供参考。

AM-FM算子分解方法在滚动轴承故障诊断中的应用

基于算子的零空间追踪算法能够实现复杂信号的自适应分解,其关键在于信号模型的构造与求解。通过定义一种新的可完全消除调幅调频信号的调幅调频算子(AFO),进一步建立了一种基于AFO的信号分解新模型。为了提高参数对信号分解的鲁棒性,将非参数正则化(NPR)方法用于解决上述模型的约束优化问题,提出了一种基于NPR的自适应信号分解方法——NPR-AFO。论文将NPR-AFO方法引入到机械故障诊断中,并通过仿真和滚动轴承局部故障实测数据分析,与现有的其他分解方法进行了对比。结果表明:所提方法不仅可以有效的提取故障特征,而且状态故障特征更加明显。

基于小波阈值降噪算法的滚动轴承故障诊断

滚动轴承因平稳的运行特性广泛用于工业生产领域,其安全稳定运行对工业生产有重要意义.针对滚动轴承的故障诊断问题,提出基于小波阈值降噪(wavelet threshold denoising,简称WTD)算法.研究结果表明:相对于其他3种算法,WTD算法具有较强的故障诊断能力.因此,WTD算法具有有效性.

火电机组深度调峰工况下炉侧蓄热系数对一次调频能力的影响分析

为研究火电机组深度调峰工况下炉侧蒸发段、过热段蓄热系数对机组一次调频能力的影响,以暂态稳定程序PSD-BPA中的典型模型为基础,同时考虑火电机组实际以炉跟机协调方式下的控制逻辑,搭建适用于火电深度调峰工况下的精细化仿真模型。通过某额定功率Pe为1 000 MW直流炉在35%Pe工况点的实际一次调频数据,验证了模型的正确性。以仿真模型为基础,定性分析深度调峰工况下炉侧蒸发段及过热段蓄热系数对机组一次调频能力的影响,结果发现:炉侧蒸发段蓄热系数越小,机组的一次调频响应能力越强;炉侧过热段蓄热系数越大,对机组一次调频越友好,通过增、减蒸发段和过热段蓄热系数可以提高机组的调频能力。另外,建立的一次调频精细化模型可以为电力生产、监管部门提供火电机组一次调频裕度分析,有利于新型电力系统的安全运行。

空化流对管路振动的影响与分析

管路系统空化流动诱导的管路振动是导致管路破坏的重要因素.重点研究流动扰动与空化的相互作用,以及对管路振动的影响.采用Zwart-Gerber-Belamri(ZGB)空化模型研究小扰动下空化云随空化数及雷诺数的动态演变规律,发现空化云会引起管路的不平衡力和流量脉动.同时,空化云会加剧不平衡力和流量脉动的脉动幅值以及改变频率的调幅变频特性.在此基础上,将空化激励等效为激励源项引入传统管路流固耦合动力模型,得到一种改进的分析管路振动空化诱导机制的流固耦合动力学模型,对空化激励下的管路进行振动求解,给出临界空化数区间,同时揭示小扰动下空化诱导管路振动的原因.所得结果对研究空化管路系统的减振降噪及安全运行具有重要意义.

单频调制的相位调制激光在频率损失下激发的幅频效应

鉴于当前对幅频效应的研究主要局限于从时域角度关注脉冲顶部调制,无法全面揭示其在频域或其它维度上的特性,从单频激光相位调制模型出发,结合理论仿真和实验验证,从波形强度调制度、激发的幅度调制信号强度和频谱分布变化等角度,研究了单阶次频率损失、整体频率损失以及调制深度变化对幅频效应激发的影响。研究结果表明,随着相位调制激光偏离滤波器中心位置距离增大,波形强度调制度随之增强,但激发的调制信号强度则呈现先上升后下降的趋势;与单阶次频率损失相比,整体频率损失所激发的幅频效应中,调制信号主要集中在基频和二次谐波上;此外,调制深度的增加会导致光谱宽度增大以及激发的调制信号强度增强。

基于最优动态功率补偿的先进绝热压缩空气储能一次调频控制策略

随着大规模新能源接入电网,新型电力系统“低惯量、弱支撑”特征凸显,电网频率调节资源日益稀缺,系统频率稳定问题愈发严峻。先进绝热压缩空气储能(advanced adiabatic compressed air energy storage,AA-CAES)具有容量大、寿命长等优势而受到广泛关注,但由于其储能和释能过程涉及气-热动态耦合过程,调频特性较为复杂,调频潜力还有待挖掘。因此,首先建立AA-CAES系统全工况动态仿真模型,进而基于期望频率动态曲线设计AA-CAES系统调频传递函数,优化目标传递函数关键参数,实现AA-CAES最小动态功率补偿下满足系统频率调节需求。最后通过仿真实验,验证了所提控制策略可优化AA-CAES调频容量的同时减小系统的稳态频率偏差与频率超调量,显著改善频率响应特性,为建设电网友好型AA-CAES电站提供技术支撑。