A lightweight cell switching and traffic offloading scheme for energy optimization in ultra-dense heterogeneous networks

One of the major capacity boosters for 5G networks is the deployment of ultra-dense heterogeneous networks (UDHNs). However, this deployment results in a tremendous increase in the energy consumption of the network due to the large number of base stations (BSs) involved. In addition to enhanced capacity, 5G networks must also be energy efficient for it to be economically viable and environmentally friendly. Dynamic cell switching is a very common way of reducing the total energy consumption of the network, but most of the proposed methods are computationally demanding, which makes them unsuitable for application in ultra-dense network deployment with massive number of BSs. To tackle this problem, we propose a lightweight cell switching scheme also known as Threshold-based Hybrid cEll swItching Scheme (THESIS) for energy optimization in UDHNs. The developed approach combines the benefits of clustering and exhaustive search (ES) algorithm to produce a solution whose optimality is close to that of the ES (which is guaranteed to be optimal), but is computationally more efficient than ES and as such can be applied for cell switching in real networks even when their dimension is large. The performance evaluation shows that THESIS significantly reduces the energy consumption of the UDHN and can reduce the complexity of finding a near-optimal solution from exponential to polynomial complexity.     

Pattern transition and regulation in a subthalamopallidal network under electromagnetic effect

Although the significant roles of magnetic induction and electromagnetic radiation in the neural system have been widely studied, their influence on Parkinson's disease (PD) has yet to be well explored. By virtue of the magnetic flux variable, this paper studies the transition of firing patterns induced by magnetic induction and the regulation effect of external magnetic radiation on the firing activities of the subthalamopallidal network in basal ganglia. We find: (i) The network reproduces five typical waveforms corresponding to the severity of symptoms: weak cluster, episodic, continuous cluster, episodic, and continuous wave. (ii) Magnetic induction is a double-edged sword for the treatment of PD. Although the increase of magnetic coefficient may lead the physiological firing activity to transfer to pathological firing activity, it also can regulate the pathological intensity firing activity with excessive β-band power transferring to the physiological firing pattern with weak β-band power. (iii) External magnetic radiation could inhibit continuous tremulous firing and β-band power of subthalamic nucleus (STN), which means the severity of symptoms weakened. Especially, the bi-parameter plane of the regulation region shows that a short pulse period of magnetic radiation and a medium level of pulse percentage can well regulate pathological oscillation. This work helps to understand the firing activity of the subthalamopallidal network under electromagnetic effect. It may also provide insights into the mechanisms behind the electromagnetic therapy of PD-related firing activity.     

基于视觉辐条图案识别方法的蓝宝石引晶机制研究

工业生产蓝宝石晶体过程中,引晶步骤有着至关重要的地位。引晶必须在温度梯度较小,温度分布趋于稳定的条件下进行。目前,工业生产蓝宝石主要依靠人工经验操控籽晶杆实现引晶操作,但是人工引晶操作的准确性不高会导致成品品质不佳、资源浪费。为此,本文提出一种基于蓝宝石视觉辐条图案识别方法来检测蓝宝石熔体状态自由液面状态,从而实现一种高效率引晶的机制。此方法利用经典骨架化算法细化辐条图案,Harris算子实现特征信息的提取,提取的特征信息放入运动轨迹模型中判断熔体稳定性,分析液面温度分布稳定性从而实现引晶。结果表明,此算法具有有效性,蓝宝石晶体引晶效率大大提高,生产出的成品良率也有提升,可有效指导蓝宝石的工业生产。     

基于PI法的门源MS6.4地震前震中附近地震热点图像异常变化研究

基于1980年以来青海省和甘肃省区域地震台网的定位地震目录，分析了研究区最小完备震级，选取空间网格尺度为0.2°×0.2°、地震活动异常学习时间段和预测时间段均为3 a，应用图像信息（PI）法，分析了门源M_S6.4地震发生前震中附近地震热点图像的异常变化过程。结果表明，在2013年1月1日至2016年1月1日的预测时间窗内，冷龙岭断裂和祁连山北缘断裂附近存在明显的地震热点，且地震热点图像颜色偏深，发震概率较高，向前滑动至2014年1月1日至2017年1月1日，2015年1月1日至2018年1月1日和2016年1月1日至2019年1月1日3个预测时间窗，此两断裂附近仍存在地震热点，地震热点图像颜色逐渐由深变浅，而门源M_S6.4地震就落在PI法得到的地震热点内。门源M_S6.4地震前存在明显的地震热点，且地震热点相对集中，地震热点图像颜色由深变浅，震后消失；在祁连山北缘断裂附近，地震热点持续存在，分布较集中，地震热点图像颜色也呈由深变浅的过程。未来需关注祁连山北缘断裂，附近有发生强震的可能。     

1980—2018年镇赉县湿地景观格局变化与人为干扰的关系

以吉林省最大湿地保留区镇赉县为研究区，基于1980—2018年8期土地利用数据，采用网格分析法研究湿地景观格局变化规律及景观指数与人为干扰度的关系。结果表明：（1）镇赉县湿地面积减少290.7 km2，水体、滩地、沼泽变化率分别为-0.45，-2.97和-4.84 km²·a^-1。（2）镇赉县湿地率（PLAND）下降6.1%，且从西北部向东南部逐渐递增；斑块数量（NP）与斑块平均面积（AREA_MN）均呈先上升后下降的趋势，东南部湿地景观破碎化加剧，中部破碎化减缓；湿地连通度的空间分布格局为西北向东南递增，斑块结合度指数（COHESION）在中部地区显著增加，在东南部地区缓慢降低。（3）镇赉县湿地人为干扰度逐渐增强、耕地面积的增加和交通网的扩张是镇赉县湿地面积萎缩、景观破碎化加剧和连通度降低的主要人为原因。人为干扰度与NP呈显著正相关，与PLAND、AREA_MN、COHESION均呈负相关。稳定西南部和东北部耕地中湿地斑块，进一步加强中部湿地水体连通性，排查东南部湿地核心区违规建筑，实施分区治理，加强对镇赉县现有湿地的保护，以期实现区域可持续发展。     

A new periodic pattern with five‐neighbored domain packing from ABC triblock terpolymer/B homopolymer blend

Self‐assembled structures from poly(isoprene‐b‐styrene‐b‐2‐vinylpyridine)(ISP)/styrene homopolymer blend were investigated. Five terpolymers whose total molecular weight, M, is in the narrow range of 121k < M < 214k, and volume fractions of the center block polystyrenes, ?_S, are similar at around 0.55, were prepared as parent block terpolymers. Their ?_P/?_I ratios, used as an indicator of asymmetry, are varied in the range 0.32 < ?_P/?_I < 2.46. Three low‐molecular weight styrene homopolymers with molecular weights of 3k, 9k, and 12k, respectively, were mixed with those block terpolymers to produce blends with almost constant styrene content within the range 0.65 < ?_S < 0.68. Both ISP/S(3k) and ISP/S(12k) blend series show a morphological transition from tetragonally packed cylinders (TPC) to double hexagonal structure (DHS) with hexagonally arrayed polyisoprene cylinders, each surrounded by six thin cylinders as satellites. If one focuses on ISP‐III(150k)/S blends whose ?_P/?_I is 0.88, TPC for ISP‐III/S(3k) was transformed to DHS for ISP‐III/S(12k), evidently due to the molecular weight effect of the added homopolymer. Finally a new periodic pattern, having P cylinders surrounded by five I cylinders each, has been discovered from ISP‐III/S(9k) at overall composition of ?_I/?_S/?_P = 0.17/0.68/0.15 and polystyrene block/styrene homopolymer ratio of w_S(b)/w_S(h) = 1.4. This structure was confirmed to possess hexagonal symmetry with larger unit cell than regular patterns ever known by X‐ray diffraction experiment. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 907–911     

Time-averaged flow characteristics and mixing properties of double-concentric jets

We examined the flow behaviors and mixing characteristics of double-concentric jets using laser-assisted smoke flow visualization method to analyze typical flow patterns and binary boundary detection technique to investigate jet spread width. Time-averaged velocity vectors, streamline patterns, velocity distributions, turbulence properties, and vorticity contours were analyzed using Particle Image Velocimetry (PIV). Topological flow patterns were analyzed to interpret the vortical flow structures. Mixing properties were investigated using a tracer-gas concentration detection method. Four characteristic modes were observed: annular flow dominated mode, transition mode, central jet dominated mode-low shear, and central jet dominated mode-high shear. The jets’ mixing properties were enhanced by two major phenomena: the merging of annular flow and central jet at the centerline and the large turbulence fluctuations produced in the flow field. The merging of the jets induced stagnation points on the central axis in the annular flow dominated mode, which caused reverse flow on the central axis and drastic turbulence fluctuations of the near field region. When the central jet penetrated the recirculation region in the other three modes, the stagnation points on the central axis and the reverse flow vanished. Therefore, the mixing behaviors were prominently enhanced in the annular flow dominated mode.     

Diffusive search with spatially dependent resetting

We consider a stochastic search model with resetting for an unknown stationary target $a\in \mathbb{R}$ with known distribution $\mu$. The searcher begins at the origin and performs Brownian motion with diffusion constant $D$. The searcher is also armed with an exponential clock with spatially dependent rate $r=r\left(\cdot \right)$, so that if it has failed to locate the target by the time the clock rings, then its position is reset to the origin and it continues its search anew from there. Denote the position of the searcher at time $t$ by $X\left(t\right)$. Let $E_0^{\left(r\right)}$ denote expectations for the process $X\left(\cdot \right)$. The search ends at time $T_a=inf\{t\ge 0:X\left(t\right)=a\}$. The expected time of the search is then ${\int }_{\mathbb{R}}\left(E_0^{\left(r\right)}{T}_a\right)\mu \left(da\right)$. Ideally, one would like to minimize this over all resetting rates $r$. We obtain quantitative growth rates for $E_0^{\left(r\right)}{T}_a$ as a function of $a$ in terms of the asymptotic behavior of the rate function $r$, and also a rather precise dichotomy on the asymptotic behavior of the resetting function $r$ to determine whether $E_0^{\left(r\right)}{T}_a$ is finite or infinite. We show generically that if $r\left(x\right)$ is of the order ${\left|x\right|}^{2l}$, with $l>-1$, then $log{E}_0^{\left(r\right)}{T}_a$ is of the order ${\left|a\right|}^{l+1}$; in particular, the smaller the asymptotic size of $r$, the smaller the asymptotic growth rate of $E_0^{\left(r\right)}{T}_a$. The asymptotic growth rate of $E_0^{\left(r\right)}{T}_a$ continues to decrease when $r\left(x\right)\sim \frac{D\lambda }{x^2}$ with $\lambda >1$; now the growth rate of $E_0^{\left(r\right)}{T}_a$ is more or less of the order ${\left|a\right|}^{\frac{1+\sqrt{1+8\lambda }}{2}}$. Note that this exponent increases to $\infty$ when $\lambda$ increases to $\infty$ and decreases to 2 when $\lambda$ decreases to 1. However, if $\lambda =1$, then $E_0^{\left(r\right)}{T}_a=\infty$, for $a\ne 0$. Our results suggest that for many distributions $\mu$ supported on all of $\mathbb{R}$, a near optimal (or optimal) choice of resetting function $r$ in order to minimize ${\int }_{{\mathbb{R}}^d}\left(E_0^{\left(r\right)}{T}_a\right)\mu \left(da\right)$ will be one which decays quadratically as $\frac{D\lambda }{x^2}$ for some $\lambda >1$. We also give explicit, albeit rather complicated, variational formulas for ${inf}_{r\gneqq 0}{\int }_{{\mathbb{R}}^d}\left(E_0^{\left(r\right)}{T}_a\right)\mu \left(da\right)$. For distributions $\mu$ with compact support, one should set $r=\infty$ off of the support. We also discuss this case.