Superposition Effect of Passive Intermodulation for Cable Assemblies with Discrete Point-Sources

In order to expand the cell coverage of wireless cellular systems, the number of passive components in wireless systems has been substantially increased. There can be many passive intermodulation(PIM) pointsources even in a device or a radio link, which may add up constructively or destructively. A modified point-source model with lossy components is proposed to evaluate the superposition effect of the forward and refl ected PIM in case of series connection. The index of the series connection factor(SCF) is employed for systems that incorporate multiple PIM sources to predict the important characteristics of the cumulative PIM, such as the maximum and minimum values and the limit form. Furthermore, some initial experimental results are given out and the deviation in the above-mentioned prediction is also analyzed.

Gravitational Faraday effect in curved space-time induced by high-power lasers

Gravitational field produced by high-power laser is calculated according to the linearized Einstein field equation in weak field approximation. Gravitational Faraday effect of electromagnetic wave propagating in the above gravitational field is studied and the rotation angle of polarization plane of electromagnetic wave is derived. The result is discussed and estimated under the condition of present experiment facility.

Was Polchinski Wrong? Colombeau Distributional Rindler Space-Time with Distributional Levi-CivitàConnection Induced Vacuum Dominance. Unruh Effect Revisited

The vacuum energy density of free scalar quantum field in a Rindler distributional space-time with distributional Levi-Cività connection is considered. It has been widely believed that, except in very extreme situations, the influence of acceleration on quantum fields should amount to just small, sub-dominant contributions. Here we argue that this belief is wrong by showing that in a Rindler distributional background space-time with distributional Levi-Cività connection the vacuum energy of free quantum fields is forced, by the very same background distributional space-time such a Rindler distributional background space-time, to become dominant over any classical energy density component. This semiclassical gravity effect finds its roots in the singular behavior of quantum fields on a Rindler distributional space-times with distributional Levi-Cività connection. In particular we obtain that the vacuum fluctuations have a singular behavior at a Rindler horizon . Therefore sufficiently strongly accelerated observer burns up near the Rindler horizon. Thus Polchinski’s account doesn’t violate the Einstein equivalence principle.

Enhanced soft magnetic properties of SiO_(2)-coated FeSiCr magnetic powder cores by particle size effect

It has been known that metal FeSiCr powders with large average particle sizes have been typically employed to prepare magnetic powder cores(SMCs),with few studies reported on the influence of magnetic properties for original powders with various average particle sizes less than 10m.In this work,SiO_(2)-coated FeSiCr SMCs with different small particle sizes were synthesized using the sol-gel process.The contribution of SiO_(2)coating amount and voids to the soft magnetic properties was elaborated.The mechanism was revealed such that smaller particle sizes with less voids could be beneficial for reducing core loss in the SMCs.By optimizing the core structure,permeability and magnetic loss of 26 and 262 kW/cm^(3)at 100 kHz and 50 mT were achieved at a particle size of 4.8m and ethyl orthosilicate addition of 0.1 mL/g.The best DC stacking performance,reaching 87%,was observed at an ethyl orthosilicate addition rate of 0.25 mL/g under 100 Oe.Compared to other soft magnetic composites(SMCs),the FeSiCr/SiO_(2)SMCs exhibit significantly reduced magnetic loss.It further reduces the magnetic loss of the powder core,providing a new strategy for applications of SMCs at high frequencies.

Design and Implementation of a High-Sensitivity Magnetic Sensing System Based on GMI Effect

A high-sensitivity magnetic sensing system based on giant magneto-impedance(GMI)effect is designed and fabricated.The system comprises a GMI sensor equipped with a gradient probe and an signal acquisition and processing module.A segmented superposition algorithm is used to increase target signal and reduce the random noise.The results show that under unshielded,room temperature conditions,the system achieves successful detection of weak magnetic fields down to 2 pT with a notable sensitivity of 1.84×10^(8)V/T(G=1000).By applying 17 overlays,the segmented superposition algorithm increases the power proportion of the target signal at 31 Hz from6.89%to 45.91%,surpassing the power proportion of the 2 Hz low-frequency interference signal.Simultaneously,it reduces the power proportion of the 20 Hz random noise.The segmented superposition process effectively cancels out certain random noise elements,leading to a reduction in their respective power proportions.This high-sensitivity magnetic sensing system features a simple structure,and is easy to operate,making it highly valuable for both practical applications and broader dissemination.

Interaction between cracks and effect of microcrack zone on main crack tip

Mechanism interaction between cracks with different orientation angles is analyzed based on the principle of superposition and a flattening method. It is found that the maximum interaction effect does not occur when the microcrack is along the direction parallel or perpendicular to the principal tensile stress, which is different from the conclusion drawn by Ortiz （1987）. The mechanism of microcrack generation and the effect of the microcrack zone on the main crack tip are studied. It is concluded that the microcrack zone has effect on the main crack tip, which increases with the increase of microcrack density and length.

Orbital effect in the stationary axisymmetric field

This paper uses an elegant mathematical method to calculate the orbital effects in the axisymmetric field created by the spinning mass with electric charge and a large number of magnetic monopoles. In comparison with that in the Reissner-Nordstroem （R-N） field, the correction terms caused by the spinning mass decrease the advanced effect as the revolution direction of the test particle coincides with that of the Kerr field, however, the correction terms caused by the spinning charged mass increase the advance effect as the revolution direction of the test particle coincides with that of the Kerr-Newman-Kasnya （KNK） field. Generalizing the effect in the axisymmetric field, it obtains interesting results by discussing the parameters of the celestial body, these parameters provide a feasible experimental verification of the general relativity.

BACKSIDE EFFECT OF BISTATIC AIRBORNE CLUTTER CHARACTERISTICS AND ITS APPLICATIONS IN GMTI

An interesting clutter characteristic of bistatic radars is presented, which is named as backside effect. In such an effect, the range-dependent ground clutter spectrum can be easily aligned, and Space-Time Adaptive Processing (STAP) is to be more applicable and effective for the Ground Moving Target Indication (GMTI) in bistatic systems. The backside effect is proved by the numerical calculation method and explained in point of the geometry. At last a new spectrum aligning method is induced, i.e., ADC and Rotation (ADCR), which can gain a further performance improvement on GMTI.

富水砂卵石地层盆形冻结止水技术研究

为解决全断面砂卵石地层地下工程的地下水控制问题,提出盆形冻结止水技术。首先,采用三轴力学试验研究冻结砂卵石的压缩力学特性和蠕变力学特性;然后,采用大尺度物理模型试验和数值模拟方法研究盆形冻结的温度场扩展规律,并根据研究结果进一步提出盆形冻结积极冻结期的群孔布置技术和维护冻结期的精细化控制技术。结果表明:1)低围压(小于3 MPa)条件下,三轴抗压强度与围压呈正线性相关,然后围压继续增大时,强度基本不变;基于损伤理论建立冻结砂卵石全过程蠕变模型。2)荷载对冻胀率及融沉系数影响最大,细粒土质量分数次之,原状饱和砂卵石是不冻胀材料,并由此建立饱和砂卵石冻胀率及融沉系数三维预测模型。3)基于大型物理模型试验及数值模拟结果,盆形冻结可以在地下水渗流条件下形成完整的盆形结构,起到有效止水的效果。4)盆底冻结管在冻结过程中表现出与单管冻结迥异的“群孔效应”,根据试验结果提出包含冻结管间距、土体导热系数、渗流速度3因素的积极冻结期冻结管合理间距的确定与布置技术。5)为节约维护冻结期的能源,提出隔排切割冻结管、仅保留盆壁冻结管2种维护形式以对冻结区域进行精细化控制,经过分析,2种方式均可以有效满足盆形结构维护期的冷量供给,保持完整的盆形形态。

地铁车站明暗挖施工引起的地表沉降叠加效应研究

为满足复杂环境下大型地下空间的高效开发需求,地下工程采用明暗挖工法进行组合施工的趋势日益明显。而近距离的明挖与暗挖施工会产生地层沉降叠加效应,研究其规律对于施工控制及环境安全较重要。以徐州地铁彭城广场站工程为背景,采用文献调研及数值模拟法对明暗挖组合式地铁车站开挖施工引起的地表变形规律进行研究,并与单一形式的明挖和暗挖引起的地表沉降特征进行对比。研究结果表明,明暗挖施工引起的地表沉降叠加效应与两者的先后开挖顺序及基坑与隧道间距相关。地表沉降叠加形态随基坑与隧道间距变化,随着基坑与隧道间距的增加地表沉降形态从单凹槽形变为双凹槽形;先明挖后暗挖顺序下暗挖隧道施工引起的最大地表沉降增加,先暗挖后明挖顺序下明挖基坑施工引起的最大地表沉降减小。

Geological effects in tectonic superposition of Paleo-Pacific domain and Paleo-Asian domain in northern part of North China

The northern part of North China is located where the Paleo-Asian domain is superposed by the Pa-leo-Pacific domain. The period from the end of the Late Paleozoic to the beginning of the Mesozoic is important for the superposition of the two domains. It is demonstrated according to the coupling of the superficial and deep geological effects that in this period begins the lithosphere modulation, hot interface uprising, and crust extension in this area. Thus a new understanding about the Indo-China movement has arisen.

Performance of a two-state quantum engine improved by the superposition effect

The performance of a two-state quantum engine under different conditions is analyzed. It is shown that the efficiency of the quantum engine can be enhanced by superposing the eigenstates at the beginning of the cycle. By employing the finite-time movement of the potential wall, the power output of the quantum engine as well as the efficiency at the maximum power out- put （EMP） can be obtained. A generalized potential is adopted to describe a class of two-level quantum engines in a unified way. The results obtained show clearly that the performances of these engines depend on the external potential, the geometric configuration of the quantum engines, and the superposition effect. Moreow^r, it is found that the superposition effect will en- large the optimally operating region of quantum engines.

断层交会对地下支护洞室围岩变形影响研究

赋存于地下洞室区域的断层是围岩开挖变形与稳定的主要影响与控制因素,而与单断层条件相比,断层交会条件下围岩变形特征和破坏机制将更为复杂。结合浙江磐安抽水蓄能电站主变排风洞的工程地质条件和支护方案,以FLAC 3D为工具模拟支护条件下双断层交会区地下洞室的围岩变形,并比较无断层、仅断层F1存在、断层F1与F2交会3种情况下围岩的变形差异。结果表明:单断层经过洞室时,断层上盘围岩有向断层倾向方向水平变形的趋势,下盘围岩变形方向相反,支护条件下单断层对位于断层上盘的围岩变形起主控作用;双断层交会时围岩变形体现出明显的断层叠加效应,但是由于预应力锚索等支护措施干预、断层与洞室相交情况差异等因素的存在,叠加效应带来的变形增长现象仅在围岩部分位置较为明显;仅存在单断层时,洞室围岩变形随着断层强度提升而减小,双断层交会时断层强度对洞室变形的影响仅在洞室部分位置呈现清晰规律,开展断层力学参数反演时应优先考虑使用这些位置的监测数据。

价格调控策略对城市道路交通减污降碳协同增效影响研究

在碳达峰目标导向下,城市道路交通减污降碳的协同增效策略研究已成为国家的紧迫任务。文章引入价格调控型策略,构建道路交通减污降碳的系统动力学模型。通过动态仿真,揭示中长期隐藏的负效应,发现:机动车污染收费通过三个途径(降低机动车出行吸引度、抑制机动车增长吸引度、增加公共交通的投资)来实现减污降碳目的;罚款和补贴政策分别通过降低机动车非法出行量和提升公共交通供给水平来促进道路交通减污降碳的治理;叠加效应将引发一系列副作用:加剧交通拥堵程度、抑制机动车减污和降碳的协同治理、增加健康风险及安全隐患。

顺层钻孔有效抽采半径影响因素及布孔间距研究

为确定顺层钻孔瓦斯抽采半径影响因素及布孔间距,基于贵州土层矿M12煤层赋存条件,建立瓦斯运移的多物理耦合数值模型,通过改变单一因素数值分析其对抽采半径的影响效果,并对单一钻孔和多钻孔抽采半径进行模拟研究。结果发现,通过流量法确定,在抽采时间达150 d时,抽采半径计算为2.2 m;由模拟分析发现抽采半径随着时间的延长不断增大,随钻孔孔径的增大而增大,随煤层初始渗透率的增大而增大,且增大的幅度随着抽采时间的延长而增涨,而抽采负压对有效抽采半径几乎没有影响;数值模拟分析表明,在抽采时间达150 d时,抽采半径模拟结果为2.1 m,受相邻钻孔抽采叠加的影响,其多钻孔抽采半径相对单个钻孔有所增大,约为单钻孔抽采半径的1.76倍,研究结果为现场合理布置抽采钻孔提供一定的理论依据。

Superposition effect of passive inter-modulation for systems operating in multiple carriers

Nowadays, more carriers and components are used in cellular networks to satisfy the requirement of high-speed data service. The increase of carriers and components may result in serious problem of passive inter-modulation （PIM）. This paper investigates the superposition effect of 3rd-order and 5th-order PIM under multicarrier scenarios with the channelized scheme （CS） and the multiplexed scheme （MS）. We use the concept of ＇effective hit＇ and the cumulative inter-modulation factors （CIFs） to evaluate the cumulative PIM product strength on each individual carrier within the receive signal band. Furthermore, with the simulator based on Monte-Carlo method, the group inter-modulation factor （GIF） is calculated to measure the average superposition effect for multiple carriers compared with the benchmark case. The simulation results show that, compared with the CS, the strength of PIM product with the MS does not increases so greatly with the growth of the total number of the carriers. The results are useful for the component designers and the cellular network planners.

深大异形基坑施工方案可行性的模拟验证

考虑到项目施工对毗邻建筑的影响,以及基坑开挖时对其周边已开挖基坑引起的地表沉降叠加效应,验证方案的安全性、可行性,以江苏省南京市惠民大道项目为例,应用有限元模拟软件MIDAS模拟项目方案的可行性及周边基坑的叠加影响,验证了方案的可行性,为后续基坑的施工方法提供参考。

Forming mechanism of ultrasonic vibration assisted compression

To study the mechanism of ultrasonic vibration assisted forming,the static and vibration assisted compression tests of aluminum 1050 were carried out via a 25 kHz high-frequency ultrasonic vibration device.It is found that vibration reduces the flow resistance and improves the surface topography.The force reduction level is proportional to the ultrasonic vibration amplitude.By using numerical simulation of static and vibration assisted compression tests,the deformation characteristics of material were investigated.Throughout the vibration,the friction between the materials and tools reduces.The stress superposition and friction effects are found to be two major reasons for reducing the force.However,the force reduction because of stress superposition and friction effects is still less than the actual force reduction from the tests,which suggests that softening effect may be one of the other reasons to reduce the force.

消除影响压实趋势线地质因素的方法——以莺歌海盆地为例

莺歌海盆地第四系和上第三系地层内除异常压力和压实作用外 ,影响声波时差的因素主要有岩性变化、成岩胶结作用、地层含天然气及裂缝的存在。这些因素在地层中往往同时存在 ,难以区分和辨识。借用地震处理过程中多道曲线叠合以增强信噪比的思路 ,通过局部区块上数口井声波时差压实曲线的叠合处理 ,反映地层孔隙特征的信息量得到增强 ,是可避开或消除影响声波速度地质因素的一种有效方法。进一步将这种方法移植到地震速度谱资料的处理中 ,获得的压力预测结果得到钻井实测压力的证实。

天水市“7.25”群发性山洪地质灾害发育特征及成因分析

通过对天水市"7.25"群发性山洪地质灾害的现场调查,系统查明了此次地质灾害的灾情、致灾因素、灾害特征、致灾范围以及分布规律,分析了此次山洪地质灾害发育特征及成因。结果表明:本次由强降雨引发并加剧的地质灾害类型主要以黄土-泥岩及黄土滑坡为主,中小型沟谷泥石流、土质崩塌和土质不稳定斜坡次之。"7.25"山洪地质灾害具有普遍性、群发性、局地爆发性等特征,其隐蔽性强,潜在危害大,灾害链模式显著。灾害发生期间降雨具有强度大、范围广等特点,使区内山体岩土体饱和,显著降低了岩土体抗剪强度,加之与地震的叠加效应明显加剧了此次群发性山洪地质灾害。