foF2 Seasonal Asymmetry Time Variation at Korhogo Station from 1992 to 2002

foF2 seasonal asymmetry is investigated at Korhogo station from 1992 to 2002. We show that equinoctial asymmetry is less pronounced and somwhere is absent trough out solar cycle phase. In general, the absence of equinoctial asymmetry may be due to the fact that in equinox and for each solar cycle phase, the asymmetry is due to Russell-McPherron mechanism. The solstice anomaly or annual anomaly is always observed throughout solar cycle phase. The minimum value of ΔfoF2 is inferior than −60% seen during all solar cycle phase at 0700 LT. This annual asymmetry may be due to interplanetary corpuscular radiation.

聚对苯二甲酸乙二醇酯的动态黏弹性能

对聚对苯二甲酸乙二醇酯(PET)进行不同频率下的温度扫描试验和不同温度下的频率扫描试验,得到PET材料的玻璃化转变温度及动态黏弹性参数随测试温度、频率的变化特性。根据时间-温度等效原理构建出宽广频域的PET动态黏弹性主曲线,得到相应的移位因子,利用WLF方程对温度移位因子进行拟合,拟合结果与试验结果吻合较好。此外,研究表明,PET损耗模量主曲线和损耗因子主曲线均呈现明显的峰值,且峰值两边具有非对称性,因此,引入改进的分数阶Zener模型(mFDZ)对PET的动态黏弹性试验主曲线进行综合分析,通过建立合适的目标函数,基于Matlab平台对mFDZ模型进行参数识别,得到了统一的模型参数值。根据得到模型参数计算的mFDZ模型曲线与PET黏弹性试验主曲线、非对称的Cole-Cole曲线及Wicket曲线均吻合良好,这表明,mFDZ模型能较好地描述PET材料动态黏弹性的非对称性,可适用于描述PET材料在宽广频域内的动态黏弹性能。

基于非对称性的碳市场与新能源市场间动态风险溢出效应研究

为有效应对碳金融风险的发生和传导,以碳市场、新能源市场的市场价格作为研究对象,基于时变Copula-CoVaR模型,探究两市场间的风险溢出方向及动态特征。研究表明:碳市场和新能源市场间存在正向相依关系以及正向非对称的风险溢出效应,其中碳市场是主要的风险接收方;碳市场和各新能源市场的风险溢出强弱顺序与相依性程度顺序一致,依次是:新能源市场、风电市场、光伏市场、新能源车市场;市场自身完善程度、政府宏观政策、外部突发事件等因素都会加剧市场间的风险溢出波动。

Effect of interplanetary magnetic field B_(x)on the polar electrojets as observed by CHAMP and Swarm satellites

Based on 16 years of magnetic field observations from CHAMP and Swarm satellites,this study investigates the influence of the Interplanetary Magnetic Field(IMF)Bx component on the location and peak current density of the polar electrojets(PEJs).We find that the IMF Bx displays obvious local time,seasonal,and hemispherical effects on the PEJs,as follows:(1)Compared to other local times,its influence is weakest at dawn and dusk.(2)In the midnight sectors of both hemispheres,the IMF Bx tends to amplify the westward PEJ when it is<0 in the Northern Hemisphere and when it is>0 in the Southern Hemisphere;this effect is relatively stronger in the local winter hemisphere.(3)At noontime,the IMF Bx intensifies the eastward current when it is<0 in the Northern Hemisphere;in the Southern Hemisphere when it is>0,it reduces the westward current;this effect is notably more prominent in the local summer hemisphere.(4)Moreover,the noontime eastward current shifts towards higher latitudes,while the midnight westward current migrates towards lower latitudes when IMF Bx is<0 in the Northern Hemisphere and when it is>0 in the Southern Hemisphere.

低握力及握力不对称对老年结直肠癌患者术后结局的预测效能研究

目的观察低握力及握力不对称对老年结直肠癌患者多种术后结局的预测效能。方法选取2022年11月—2023年6月257例老年结直肠癌患者为研究对象,收集所有患者的一般资料、握力指标及术后不良结局等数据。通过Logistic回归分析探讨低握力及握力不对称与术后结局的关系。绘制受试者工作特征曲线,分析握力值及握力比值单独与联合应用对患者并发症的预测效能。结果握力值、握力比值、握力值联合握力比值可有效预测并发症的发生情况,曲线的曲线下面积(AUC)和(95%CI)分别为0.649(0.587~0.707)、0.627(0.565~0.686)、0.672(0.611~0.729)。握力比值、握力值联合握力比值可有效预测住院时间延长,AUC(95%CI)分别为0.671(0.610~0.728)、0.577(0.514~0.638)。握力值、握力值联合握力比值可有效预测衰弱的发生,AUC(95%CI)分别为0.585(0.522~0.646)、0.586(0.523~0.647)。结论本研究创新性地揭示了多种握力指标对结直肠癌患者术后结局的预测效能,低握力及握力不对称可有效预测患者并发症的发生,握力不对称可有效预测患者住院时间延长,低握力可有效预测患者衰弱的发生。

基于洛伦茨曲线的降雨时间分布均匀度变化

本文提出了基于洛伦茨曲线的降雨时间分布均匀度变化方法,为新疆农耕提供降雨分布数据。该方法以洛伦茨曲线原理为基础,依据降雨时间分布均匀度基尼系数和洛伦茨不对称系数指标,建立了降雨时间分布均匀度评价模型。以新疆作为研究对象,研究结果表明:新疆在2006年、2016年和2018年的降雨时间分布基尼系数较大,其降雨时间分布不够均匀。

测量互联网环境的单向延迟及不对称性研究

NTP协议(Network Time Protocol)的出现就是为了解决网络内设备系统时钟的同步问题。不幸的是,在通常的互联网环境中,数据传输的延迟不是恒定的,即使相同的路由,从NTP服务器到NTP客户端延迟与从NTP客户端到NTP服务器延迟,即单向延迟(OWD)不总是相同的。这对时间同步的准确性有很大的影响。目前广泛应用的PTP也同样存在这个问题。因此,为了提高时间的准确性,需要通过测量,提供有关实际传输OWD的时间分布和OWD的不对称性的研究。

Western Pacific Warm Pool and ENSO Asymmetry in CMIP3 Models

Theoretical and empirical studies have suggested that an underestimate of the ENSO asymmetry may be accompanied by a climatologically smaller and warmer western Pacific warm pool. In light of this suggestion, simulations of the tropical Pacific climate by 19 Coupled Model Intercomparison Project Phase 3 （CMIP3） climate models that do not use flux adjustment were evaluated. Our evaluation revealed systematic biases in both the mean state and ENSO statistics. The mean state in most of the models had a smaller and warmer warm pool. This common bias in the mean state was accompanied by a common bias in the simulated ENSO statistics： a significantly weak asymmetry between the two phases of ENSO. Moreover, despite the generally weak ENSO asymmetry simulated by all models, a positive correlation between the magnitude of the bias in the simulated warm-pool size and the magnitude of the bias in the simulated ENSO asymmetry was found. These findings support the suggested link between ENSO asymmetry and the tropical mean state--the climatological size and temperature of the warm pool in particular. Together with previous studies, these findings light up a path to improve the simulation of the tropical Pacific mean state by climate models： enhancing the asymmetry of ENSO in the climate models.

Study on the local time asymmetry of the Earth's ring currents based on multiple low-Earth-orbit satellite magnetic observations

The azimuthal morphology of Earth's ring currents has consistently shown asymmetry during extreme space weather events at low latitudes,particularly during geomagnetic storms.A dawn-dusk pattern has been detected during the storm main phase through near-Earth and in-situ magnetic measurements.This asymmetry is believed to arise from asymmetric solar windmagnetosphere coupling and is linked to the closure of the ring current.Recent evidence has confirmed the existence of asymmetric ring currents during quiet times and the storm recovery phase.This phenomenon may be closely related to the evolution of ring currents,including plasma injection and decay processes.In this study,the local time asymmetry of the ring current is estimated using data from low-Earth-orbit Swarm and Macao Science Satellite-1(MSS-1)missions.Spherical harmonics models are developed to quantify the magnetic field of ring currents through external Gauss coefficients during both quiet periods and the storm recovery phase.Several features of dawn-dusk asymmetry are observed in various cases in different months.(1)The maximum difference in magnetic value across local time ranges from 3 to 10 nT,showing relative invariance compared with various Sym-H levels.(2)Stronger magnetic signals are detected at the premidnight sector during quiet times and at the afternoon sector during the storm recovery phase.(3)Magnetic perturbations remain at a lower level during the postmidnight and morning sectors.Although the pattern of local time asymmetry differs between quiet times and the recovery phase,dawn-dusk asymmetry remains the most pronounced feature,affecting the trapping and loss of charged particles in the inner magnetosphere.Combining Swarm and MSS-1 magnetic observations can enable convenient monitoring of the detailed azimuthal local time effects of the ring current at various disturbance levels in the future.

What does the “arrow of time” stand for?

One hundred and thirty years after the work of Ludwig Boltzmann on the interpretation of the irreversibility of physical phenomena, and one century after Einstein's formulation of Special Relativity, we are still not sure what we mean when we talk of “time” or “arrow of time”. We shall try to show that one source of this difficulty is our tendency to confuse, at least verbally, time and becoming, i.e. the course of time and the arrow of time, two concepts that the formalisms of modern physics are careful to distinguish. The course of time is represented by a time line that leads us to define time as the producer of duration. It is customary to place on this time line a small arrow that, ironically, must not be confused with the “arrow of time”. This small arrow is only there to indicate that the course of time is oriented, has a well-defined direction, even if this direction is arbitrary. The arrow of time, on the other hand, indicates the possibility for physical systems to experience, over the course of time, changes or transforma-tions that prevent them from returning to their initial state forever. Contrary to what the ex-pression “arrow of time” suggests, it is there-fore not a property of time itself but a property of certain physical phenomena whose dynamic is irreversible. By its very definition, the arrow of time presupposes the existence of a well- established course of time within which – in addition – certain phenomena have their own temporal orientation. We think that it is worth-while to emphasize the difference between sev-eral issues traditionally subsumed under the label “the problem of the direction of time”. If the expressions “course of time”, “direction of time” and “arrow of time” were better defined, systematically distinguished from one another and always used in their strictest sense, the debate about time, irreversibility and becoming in physics would become clearer.

Entropy, Biological Evolution and the Psychological Arrow of Time

We argue that in Universes where future and past differ only by the entropy content a psychological arrow of time pointing in the direction of entropy increase can arise from natural selection in biological evolution. We show that this effect can be demonstrated in very simple toy computer simulations of evolution in an entropy increasing or decreasing environment.

Elementary Particles Result from Space-Time Quantization

We justify and extend the standard model of elementary particle physics by generalizing the theory of relativity and quantum mechanics. The usual assumption that space and time are continuous implies, indeed, that it should be possible to measure arbitrarily small intervals of space and time, but we ignore if that is true or not. It is thus more realistic to consider an extremely small “quantum of length” of yet unknown value a. It is only required to be a universal constant for all inertial frames, like c and h. This yields a logically consistent theory and accounts for elementary particles by means of four new quantum numbers. They define “particle states” in terms of modulations of wave functions at the smallest possible scale in space-time. The resulting classification of elementary particles accounts also for dark matter. Antiparticles are redefined, without needing negative energy states and recently observed “anomalies” can be explained.

光纤频率传递的链路不对称性分析

基于光纤的频率传递在时频同步体系的构建与应用中占据着重要地位。为了在射频稳相传输系统中定量研究由于温度不对称和波长不对称所引入的延迟波动和色散残余等因素对系统稳定性的影响,使用光学仿真软件搭建了简易频率传递系统与3 000 km光纤链路进行10 GHz射频信号传递的仿真分析。通过分析发现链路中引入的温度不对称对系统频率稳定性影响较小,而波长不对称所导致的影响较大,随着正反向波长的差异增大,系统频率稳定性恶化量级在10^(-13)/s以上。此研究分析对实际环境下的长距离光纤频率传递系统的建设及优化具有实际指导作用。

温度对PDC法测试冲击电容器结果的影响研究

为了研究不同测试温度对冲击电容器极化去极化电流法(PDC)测试结果的影响,对未老化和热老化10天的冲击电容器分别进行了20℃、40℃、60℃、80℃下的PDC测试。通过分析不同测试温度下的极化去极化电流,得到了冲击电容器不同测试温度下的直流电导率、0.1Hz下的介质损耗因数值(tanδ)和时间常数不对称系数(τ_(as))。结果表明,随着测试温度的上升,冲击电容器热老化前后极化电流、直流电导率及0.1 Hz下的介质损耗因数值均随着测试温度的升高先增大后适当减小。而时间常数不对称系数虽然随着温度变化有一定的波动,但变化并不明显,因此,在对冲击电容器进行PDC测试时可选择时间常数不对称系数作为判断冲击电容器绝缘状态的依据。

汇率风险暴露会影响股权再融资折价吗

本文基于我国A股上市公司2006一2019年的财务数据和股权再融资数据,检验了公司汇率风险暴露与股权再融资折价的关系。研究结果表明:(1)公司的汇率风险暴露将使公司承担更高的股权再融资折价,而且公司的信息不对称程度越高,其在相同的汇率风险暴露下承担的股权再融资折价也越高;(2)公司的汇率风险暴露会带来更大的股权再融资规模,这是公司通过“择时”发行来实现的。进一步的研究表明,公司的汇率风险暴露还将引发更加显著的负向累积平均超额收益率、更昂贵的发行费用和更高的预案失败概率;“融资融券”交易可以抑制汇率风险暴露带来的股权再融资折价;严重的大股东代理问题会增加汇率风险暴露带来的股权再融资折价。

Time-reversal asymmetries in Λ_(b)→Λ(→pπ^(−))ℓ^(+)ℓ^(−)

We study the decays ofΛb→Λ(→pπ^(−))ℓ^(+)ℓ^(−)withℓ=(e,μ,τ).We examine the full angular distributions with polarizedΛb,where the T-odd observables are identified.We discuss the possible effects of new physics(NP)and find that the T-odd observables are sensitive to them as they vanish in the standard model.Special attention is given to the interference of(pseudo)scalar operators with(axial)vector operators in polarized Λ_(b)→Λ(→pπ^(−))τ^(+)τ^(−),which are studied for the first time.Their effects are proportional to the lepton masses and therefore may evade the constraint from Λ_(b)→Λ(→pπ^(−))μ^(+)μ^(−) at the LHCb naturally.AsΛ_(b)→Λ(→pπ^(−))τ^(+)τ^(−) is uncontaminated by the charmonia resonance,it provides a clean background to probe NP.In addition,we show that the experimental central value of K10 in Λ_(b)→Λ(→pπ^(−))μ^(+)μ^(−) at the LHCb can be explained by the NP case,which couples to the right-handed quarks and leptons.The polarization fraction of Λ_(b) at the LHCb is found to be consistent with zero regardless of the NP scenarios.

完全服务和非对称门限服务两级轮询系统特性分析

区分优先级的轮询服务一直是研究人员讨论并探索的热点,本文则是采用了对称性与非对称性相结合的区分优先级的两级轮询服务模型.系统依托并行方式的处理模式,既提高了轮询系统的利用率,也降低服务器在查询转换期间所耗费的时间.并且运用马尔科夫链和概率母函数的方法建立了轮询系统的数学模型,通过对数学模型的解析精确地给出了两级非对称服务系统平均排队队长及查询周期的表达式.同时,根据系统终端循环周期的二阶特性量近似相等的方法,针对两级非对称模型给出了一种平均等待时间的近似解析式.

肋板鼓风冻结装置中食品冻结时间的研究

进行了肋板鼓风双效冻结装置中食品冻结时间的理论和实验的研究。作者首先以纯水为对象 ,用实验的方法求出上侧表面传热系数 ,然后用有限差分的焓方程数值求解食品在其中的冻结时间 ,最后用实验的方法进行验证 ,表明数值求解可靠 。

基于技术进步和信息不对称的证据合成研究

证据理论著名的Dempster-Shafer合成公式忽视了证据信息源的主观差异性,导致其在应用中存在一些不合理性.本文初步研究了不同专家意见在决策中的分配、组合问题,提出了基于技术进步和信息不对称的动态证据合成规则,在设立专家权威系数和时间序列信度分配函数的基础上实现了新的合成法则.实例分析表明,新的合成公式比较符合直观和常理,并较好地解决了冲突证据的合成问题.

委托代理问题研究综述

当参与者的信息并非完全时,将出现委托代理问题。在委托代理问题相关研究中,通常假定委托人较代理人占有更多其他方面的资源,但由于种种原因,委托人不得不把工作交由他人去做。但代理人不会无偿替委托人做事,委托人必须向其支付报酬,当然明智的委托人也必定会对自己提供的报酬提出相应的要求。此时,必须求得信息不对称情况下,委托人为激励代理人朝着自己想要的方向努力而需要付出的额外成本,这就是委托代理问题希望解决的问题。而为了解委托人需要签订的契约,首先应知道委托人当前的处境,即其所面临的不对称信息的来源(主要包括隐匿行动和隐匿信息两种)及其引发的问题(逆向选择和道德风险),还有信息不对称问题发生的时序和其他限制条件。