Heuristic Estimation of the Vacuum Energy Density of the Universe: Part II-Analysis Based on Frequency Domain Electromagnetic Radiation

In Part I of this paper, an inequality satisfied by the vacuum energy density of the universe was derived using an indirect and heuristic procedure. The derivation is based on a proposed thought experiment, according to which an electron is accelerated to a constant and relativistic speed at a distance L from a perfectly conducting plane. The charge of the electron was represented by a spherical charge distribution located within the Compton wavelength of the electron. Subsequently, the electron is incident on the perfect conductor giving rise to transition radiation. The energy associated with the transition radiation depends on the parameter L. It was shown that an inequality satisfied by the vacuum energy density will emerge when the length L is pushed to cosmological dimensions and the product of the radiated energy, and the time duration of emission is constrained by Heisenberg’s uncertainty principle. In this paper, a similar analysis is conducted with a chain of electrons oscillating sinusoidally and located above a conducting plane. In the thought experiment presented in this paper, the behavior of the energy radiated by the chain of oscillating electrons is studied in the frequency domain as a function of the length L of the chain. It is shown that when the length L is pushed to cosmological dimensions and the energy radiated within a single burst of duration of half a period of oscillation is constrained by the fact that electromagnetic energy consists of photons, an inequality satisfied by the vacuum energy density emerges as a result. The derived inequality is given by where is the vacuum energy density. This result is consistent with the measured value of the vacuum energy density, which is 5.38 × 10-10 J/m. The result obtained here is in better agreement with experimental data than the one obtained in Part I of this paper with time domain radiation.

Heuristic Estimation of the Vacuum Energy Density of the Universe: Part I—Analysis Based on Time Domain Electromagnetic Radiation

In this paper, an inequality satisfied by the vacuum energy density of the universe is derived using an indirect and heuristic procedure. The derivation is based on a proposed thought experiment, according to which an electron is accelerated to a constant and relativistic speed at a distance L from a perfectly conducting plane. The charge of the electron is represented by a spherical charge distribution located within the Compton wavelength of the electron. Subsequently, the electron is incident on the perfect conductor giving rise to transition radiation. The energy associated with the transition radiation depends on the parameter L. It is shown that an inequality satisfied by the vacuum energy density will emerge when the length L is pushed to cosmological dimensions and the product of the radiated energy and the time duration of emission are constrained by Heisenberg’s uncertainty principle. The inequality derived is given by ρΛ ≤ 9.9×10-9J/m3 where ρΛ is the vacuum energy density. This result is consistent with the measured value of the vacuum energy density, which is 0.538 × 10-9J/m. Since there is a direct relationship between the vacuum energy density and the Einstein’s cosmological constant, the inequality can be converted directly to that of the cosmological constant.

Hints of the Photonic Nature of the Electromagnetic Fields in Classical Electrodynamics

Several recent publications show that the electromagnetic radiation generated by transmitting antennas satisfy the following universal conditions: The time domain radiation fields satisfy the condition A ≥ h/4π ⇒q ≥ e where A is the action of the radiation field, which is defined as the product of the radiated energy and the duration of the radiation, h is the Planck constant, e is the electronic charge and q is the charge associated with the radiating system. The frequency domain radiation fields satisfy the condition U ≥ hv ⇒q ≥ e where U is the energy radiated in a single burst of radiation of duration T/2 and v is the frequency of oscillation. The goal of this paper is to show that these conditions, which indeed are expressions of the photonic nature of the electromagnetic fields, are satisfied not only by the radiation fields generated by physical antennas but also by the radiation fields generated by accelerating or decelerating electric charges. The results presented here together with the results obtained in previous studies show that hints of the photonic nature of the electromagnetic radiation remain hidden in the field equations of classical electrodynamics, and they become apparent when the dimension of the radiating system is pushed to the extreme limits as allowed by nature.

基于Transmission3D的轮齿啮合刚度求解方法

提出了一种基于Transmission3D(T3D)的轮齿啮合刚度求解方法,该方法通过建立半有限元/半接触力学模型,保证齿轮副啮合分析的求解精度和效率。利用该方法求解了典型齿轮副的时变啮合刚度和平均啮合刚度,求解结果与ISO 6336—1996标准误差对比仅为2.6%,证明了求解方法的合理性。针对现有标准的不足,基于T3D研究了轴孔半径对啮合刚度的影响规律;结合一般有限元法进行了影响机理分析,在此基础上给出了航空齿轮系统动力学建模和模态分析时的啮合刚度处理方法。

基于Cloudsat资料的四川盆地飞机积冰特征分析

飞机积冰的发生与云微物理特征密切相关,因此积冰区的云微物理特征分析对飞机的运行安全有重要的意义。利用Cloudsat资料对2016年1月12日和14日的通航飞机积冰过程进行云微物理过程识别分析。结果表明:Cloudsat卫星对积冰过程中的云有很好的识别和探测能力;由于此次飞行高度较低,飞机积冰主要发生在在层积云和积云中,水含量最大值700 mg/m^(3),粒子半径在75μm以上,最大值在150μm以上,发生积冰的温度在-10℃~0℃,飞机积冰情况主要是轻度和中度积冰;Cloudsat卫星能够很好地识别云的类型以及云中过冷水的含量,但未能判定对流云和卷云的情况。

Active generalized predictive control of turbine tip clearance for aero-engines

Active control of turbine blade tip clearance continues to be a concern in design and control of gas turbines. Ever increasing demands for improved efficiency and higher operating temperatures require more stringent tolerances on turbine tip clearance. In this paper, a turbine tip clearance control apparatus and a model of turbine tip clearance are proposed; an implicit active generalized predictive control （GPC）, with auto-regressive （AR） error modification and fuzzy adjustment on control horizon, is presented, as well as a quantitative analysis method of robust per- turbation radius of the system. The active clearance control （ACC） of aero-engine turbine tip clear- ance is evaluated in a lapse-rate take-off transient, along with the comparative and quantitative analysis of the stability and robustness of the active tip clearance control system. The results show that the resultant active tip clearance control system with the improved GPC has favorable steadystate and dynamic performance and benefits of increased efficiency, reduced specific fuel consump- tion, and additional service life.

Thermal protection mechanism of heat pipe in leading edge under hypersonic conditions

Sharp local structure, like the leading edge of hypersonic aircraft, confronts a severe aerodynamic heating environment at a Mach number greater than 5. To eliminate the danger of a material failure, a semi-active thermal protection system is proposed by integrating a metallic heat pipe into the structure of the leading edge. An analytical heat-balance model is established from traditional aerodynamic theories, and then thermal and mechanical characteristics of the structure are studied at Mach number 6–8 for three refractory alloys, Inconel 625, C-103, and T-111. The feasibility of this simple analytical method as an initial design tool for hypersonic aircraft is assessed through numerical simulations using a finite element method. The results indicate that both the isothermal and the maximum temperatures fall but the von Mises stress increases with a longer design length of the leading edge. These two temperatures and the stress rise remarkably at a higher Mach number. Under all investigated hypersonic conditions, with a 3 mm leading edge radius and a0.15 m design length, the maximum stress exceeds the yield strength of Inconel 625 at Mach numbers greater than 6, which means a material failure. Moreover, both C-103 and T-111 meet all requirements at Mach number 6–8.

轻型飞机翼肋支柱端与端部配件的配合强度实验

飞机翼肋支柱能够支撑机翼,在飞机受到强大的气流阻力时,也可以帮助缓解飞机所承受的张力和气流压缩力。因此,优化机翼支柱设计可以大大提高飞机飞行过程中可承受的压力,从而提高飞行的安全性。翼肋支柱设计最重要的部分是支柱端与端部配件之接的连接配合,支柱与端部配件使用点焊连接。设计2种不同的支柱端连接方式:实验a是将铝质支柱端通过点焊直接固定在铁板上;实验b是将支柱一端套上一个铁袖套,同样通过点焊的方式固定在铁板上。通过实验分析对比其承受力和横向弯曲挠度。结果表明:实验a的设计方案能够更好承受住压力,有更高的安全性,更加有利于对飞机机翼支柱设计的研究。

基于PWPF调制技术的飞机飞行姿态控制系统软件设计

为实现飞机行进轨迹多波段同时调节,使其飞行姿态能够受到软件程序的有效控制,设计基于PWPF调制技术的飞机飞行姿态控制系统软件程序;根据时钟配置情况,设置CAN通信接口,并以此为基础,完成对导航仪与舵机状态的检测,再联合偏航距离校正结果,规范核心控制程序的编写形式,实现系统各软件模块功能的设计;建立自抗扰闭环,按照PWPF调制技术的静态作用需求,求解二次规划函数,完成基于PWPF调制技术的控制机制定义;在反步控制器运行过程中,推导非线性建模表达式,实现对飞机飞行姿态控制行为的建模,完成基于PWPF调制技术的飞机飞行姿态控制系统软件设计;实验结果表明,基于PWPF调制技术所设计的软件程序,在X波、C波、S波、L波的波频范围内,均能有效控制飞机的飞行姿态,与多波段调节飞机行进轨迹的实际应用诉求相符合。

Statistical and thermodynamic properties of binary self-condensing vinyl polymerization

The thermodynamic properties of a binary self-condensing vinyl polymerization system consisting of monomers and inimers are investigated by the principle of statistical mechanics.In detail,in terms of two types of canonical partition functions constructed from different viewpoints,the equilibrium free energy,the law of mass action and the size distribution of hyperbranched polymers are obtained.As an application,the specific heat,equation of state and isothermal compressibility concerning the polymerization are given as well.To study the dimension of hyperbranched polymers in the system,a recursion formula satisfied by the(k+1)-th and k-th mean square radius of gyration is derived,and then the first,second and third radius of gyration under different solvent conditions are presented.The influences of the fraction of inimers,the conversion of vinyl groups and the solvent effect on the average dimension of hyperbranched polymers are discussed.

军用机型复杂飞行动作提取与识别的方法研究

飞行动作识别及其对应飞参数据的提取是飞行训练质量分析的关键内容。现阶段的飞参数据量大、维度高、冗余数据多,为此提出了无监督聚合动态时间规整(UADTW)算法,降低动态时间规整(DTW)算法复杂度,帮助人工快速建立样本集,并提取标准序列相关性特征。同时,根据复杂飞行动作特点,构造深度神经网络模型学习飞行动作序列特征、差量特征和标准序列相关性,并在此基础上设计了自选择特征层,提出自选择深度神经网络(SDNN)模型,该模型能够自主选择对飞行动作识别较大贡献的特征,进一步提高特征表示对飞参数据的刻画。本文所提出的UADTW和SDNN飞行动作提取及识别方法能够减少人工成本,并有效提升了飞行动作识别的准确率。

Effect of spatial distance on search information correlation in complex systems

Spatial distance has a remarkable effect on the attended mode of a network embedded in a certain space. First, we investigate how spatial restriction leads to information-information correlation that is strong, linear and positive in real networks. We then construct a two-dimensional space, define the action radius R for nodes of networks, and propose a class of models that depend on spatial distance. Information correlation of the models is consistent with that of real networks. The spatial distance plays a leading role in generating assortative mixing by degree, while the generation of disassortative mixing relies on both the degree of preferential attachment and spatial restriction.

雷达网反隐身性能评估—雷达网综合发现概率

在高科技局部战争中，隐身飞机是防空雷达面临的“四大威胁”之一。雷达组网是实现反隐身的一种有效技术。以隐身飞机F-117A为对象，提出了隐身飞机姿态角的概念，根据姿态角得到计算雷达探测概率所需要的雷达截面积；提出了雷达网综合发现概率的概念和以“高度分层，平面分格”的描述方法，建立了雷达网综合发现概率数学模型，依此从雷达网发现隐身飞机的能力方面对雷达网反隐身的能力予以评估；在此基础上编制出性能评估软件，可为雷达网反隐身的实际应用和评估提供一定参考；经过运行分析发现在由3部分米波雷达和2部米波组成的雷达网的综合发现概率较单部雷达的发现概率平均提高约5％～20％。

基于作战行动航母编队兵力配置

科学合理的兵力配置是航母编队作战的前提和基础,影响航母编队兵力配置的因素很多,本文从作战行动的角度研究航母编队兵力配置问题。航母编队基本作战样式可分为对空作战、对海作战、对潜作战和对岸作战4种,基于4种基本作战样式分析了作战行动因素对航母编队兵力配置的影响与约束,并提出相应的原则与思路,有助于进一步完善航母编队兵力配置理论。

高超声速飞行器突防航迹规划仿真研究

飞行器的航迹规划是指在特定的约束条件下,寻找一条从初始点到目标点满足某种性能指标的的最优运动轨迹。合理有效的航迹对于增强飞行器的生存和突防能力都有着重要的意义。在使用栅格法规划航迹的过程中按照何种搜索策略才能在最短时间内到达下一节点是影响算法效率的重要因素。为增强高超声速飞行器的突防能力,采用改进搜索策略的蚁群优化算法求解其航迹规划问题。区别于普通自适应蚁群算法的搜索模式,算法在考虑当前节点与目标节点相对位置关系的基础上,综合考虑飞行器在中间航迹点的速度方向以及最小转弯半径的约束,进一步删减相邻搜索节点,从而达到提高算法速度的效果。针对目标节点相对初始节点在第一象限的情况进行了仿真分析。仿真验证了改进自适应蚁群算法的有效性和合理性。此外,考虑到飞行器的最小转弯半径,为保证规划的空防航迹真实有效提供了参考。

计算机仿真技术在桡骨远端骨折掌侧锁定钢板放置定位的作用研究

目的:观察探讨计算机仿真技术在桡骨远端骨折掌侧锁定钢板的放置定位的作用。方法:选取医院2013年2月-2014年7月收纳的98例桡骨远端骨折患者,按随机分配原则分为观察组和对照组,各49例。观察组桡骨远端骨折患者,应用计算机仿真技术MIMICS软件建模,测量桡骨和掌侧钢板定位,关节面边缘与掌侧钢板螺孔中心之间最佳长度,计算掌侧锁定钢板的放置定位的标准差及均值。对照组桡骨远端骨折患者,应用传统常规X射线及CT阅片计算桡骨和掌侧钢板定位。结果:两组桡骨远端骨折患者手术情况对比,观察组透视次数、手术时间均低于对照组,有明显差异,具有统计学意义(P<0.05)。结论:计算机仿真技术在桡骨远端骨折掌侧锁定钢板的放置定位的效果显著,较常规X片检查确定等方法更为精确合适计算桡骨远端骨折关节面边缘与螺孔中心之间的最佳距离,提高骨折固定的稳定性和适应性,减少治疗后透析后检查次数及时间。其临床选择优势较高,无严重不良反应,值得临床上进一步推广应用。

农药喷雾飞行器越界检测算法实现

针对当前的农药喷雾飞行器需要人工时刻观察是否飞出农田边界这一现状,提出了一种基于高斯混合模型的农药喷雾飞行器越界自动检测算法。首先,采用混合高斯模型进行目标检测,然后通过计算形状描述符获取其形状特征并进行目标识别定位,最后通过计算目标质心位置结合目标的运动方向判断其是否出界。实验结果表明:该算法能够准确地判断飞行器的越界行为,准确率达到91.31%以上。

悬浮式反鱼雷水雷设计构想

为了增加潜艇防御来袭鱼雷手段,提高潜艇的生存概率,提出了悬浮式反鱼雷水雷的设计构想,阐述了悬浮式反鱼雷水雷的基本原理,设计了系统总体结构,在此基础上说明了引信和悬浮机构的详细设计原理,并对水雷的动作半径进行了计算分析。悬浮式反鱼雷水雷可以成为潜艇防御来袭鱼雷的有力武器,为提高潜艇生命力提供有力保障。

基于电阻率和支持向量机算法的混凝土振捣范围预测

基于混凝土电阻率和支持向量机算法,提出了一种新拌混凝土振捣范围的原位预测方法。首先采集振捣过程中混凝土不同区域的电阻率数据,经小波去噪后提取特征值;将受振混凝土各区域作为样本群,以各区域的混凝土电阻率特征值、与振捣棒的相对位置以及混凝土流动性特征值作为样本信息,以振捣作用下铝球是否沉降至该区域作为分类标签,搭建支持向量机分类模型,对混凝土各个区域是否处于振捣范围内进行二分类判断,并将两类区域的分界位置作为振捣范围的表征;预测结果表明,以坍落度为60、90 mm的混凝土试验数据作为监督学习的训练组,训练得到的支持向量机分类模型能够准确预测相同振捣棒在坍落度170 mm的混凝土中的振捣范围,证明了使用电阻率数据表征新拌混凝土振捣范围的可行性。

液压作动器回中锁紧协同作用特性分析

针对某飞行器液压作动器在服役工况下的自动回中、锁紧功能需要,分析了作动器动作次序、工作机理、液体回路及锁紧部件间的协同作用机制。液压作动器各部件油液连通耦合,运动相对独立。分别建立锁紧部件力学模型、作动器活塞和锁紧销的数学模型,通过理论仿真求解运动部件的动态响应。对比动态响应幅值、速度,结合装置内部空间结构及参数范围,评估故障锁紧过程中锁紧杆和锁紧销协同作用的可行性及空间干涉问题。为保证锁紧可靠性和稳定性,提出了结构尺寸优化方案。优化结果表明:某型液压作动器在1800 N压、拉负载作用下,锁紧销与锁紧杆分别经过66 ms和90 ms的相对运动后,可实现可靠锁紧;所建立的数学模型,可为液压作动器性能可靠性和安全性提供一定理论和技术支持。