激发态的最速逼近微扰理论

本文将文献［１］提出的应用于量子体系基态的最速逼近微扰理论（ＳＡＰＴ）推广到了激发态。本文证明，只要保持激发态尝试波函数正交于对称性相同的激发态或基态波函数，就能避免计算过程的变分坍陷，并通过逐步迭代（逐一计入其他各态的贡献）计算逼近体系精确的激发态能量和相应的波函数，且不存在瑞利－薛定谔微扰理论（ＲＳＰＴ）的无穷求和和最陡下降微扰理论（ＳＤＰＴ）需计算哈密顿量二次和三次方矩阵元的困难。本文的方法可用于求精确的激发态能量和波函数。     

Microfibre-nanowire hybrid structure for energy scavenging

A self-powering nanosystem that harvests its operating energy from the environment is an attractive proposition for sensing, personal electronics and defence technologies. This is in principle feasible for nanodevices owing to their extremely low power consumption. Solar, thermal and mechanical (wind, friction, body movement) energies are common and may be scavenged from the environment, but the type of energy source to be chosen has to be decided on the basis of specific applications. Military sensing/surveillance node placement, for example, may involve difficult-to-reach locations, may need to be hidden, and may be in environments that are dusty, rainy, dark and/or in deep forest. In a moving vehicle or aeroplane, harvesting energy from a rotating tyre or wind blowing on the body is a possible choice to power wireless devices implanted in the surface of the vehicle. Nanowire nanogenerators built on hard substrates were demonstrated for harvesting local mechanical energy produced by high-frequency ultrasonic waves. To harvest the energy from vibration or disturbance originating from footsteps, heartbeats, ambient noise and air flow, it is important to explore innovative technologies that work at low frequencies (such as <10 Hz) and that are based on flexible soft materials. Here we present a simple, low-cost approach that converts low-frequency vibration/friction energy into electricity using piezoelectric zinc oxide nanowires grown radially around textile fibres. By entangling two fibres and brushing the nanowires rooted on them with respect to each other, mechanical energy is converted into electricity owing to a coupled piezoelectric-semiconductor process. This work establishes a methodology for scavenging light-wind energy and body-movement energy using fabrics.     

中国能源消费与经济增长关系的因果分析

文章从生产函数理论的新视角,利用多变量的协整检验和基于向量误差修正模型(VECM)的因果关系检验,实证分析了中国能源消费与经济增长之间的关系;结果表明,短期内中国能源消费与GDP增长之间不存在因果关系,长期内存在GDP到能源消费的单向因果关系;这一推断有重要的政策涵义,即节能政策在中国是可行的,在长期内不会影响经济的发展。     

Direct observation of the discrete character of intrinsic localized modes in an antiferromagnet

In a strongly nonlinear discrete system, the spatial size of an excitation can become comparable to, and influenced by, the lattice spacing. Such intrinsic localized modes (ILMs)--also called 'discrete breathers' or 'lattice solitons'--are responsible for energy localization in the dynamics of discrete nonlinear lattices. Their energy profiles resemble those of localized modes of defects in a harmonic lattice but, like solitons, they can move (although, unlike solitons, some energy is exchanged during collisions between them). The manipulation of these localized energy 'hotspots' has been achieved in systems as diverse as annular arrays of coupled Josephson junctions, optical waveguide arrays, two-dimensional nonlinear photonic crystals and micromechanical cantilever arrays. There is also some evidence for the existence of localized excitations in atomic lattices, although individual ILMs have yet to be identified. Here we report the observation of countable localized excitations in an antiferromagnetic spin lattice by means of a nonlinear spectroscopic technique. This detection capability permits the properties of individual ILMs to be probed; the disappearance of each ILM registers as a step in the time-dependent signal, with the surprising result that the energy staircase of ILM excitations is uniquely defined.     

(Ce,Tb) MgAl11O19绿色荧光粉的发光性质和能量传递

在还原气氛下,采用高温固相法合成了(Ce, Tb) MgAl11O19绿色荧光粉,研究了(Ce, Tb) MgAl11O19中Ce3 与Tb3 发光性质和两者之间的能量传递现象.Ce3 的发射光谱表明Ce3 由于5d轨道裸露在外壳层,很容易受到周围晶体场的影响,使得5d轨道不再是分离的能级,几乎成为能带,从而造成了Ce3 的宽带发射而不是线谱.Ce3 的发射光谱与Tb3 的激发光谱在350-450nm范围内有很大的光谱重叠,从而为两者之间的能量传递提供了良好的条件.Ce3 与Tb3 之间的能量传递方式主要以共振传递为主.     

Fast heating of ultrahigh-density plasma as a step towards laser fusion ignition

Modern high-power lasers can generate extreme states of matter that are relevant to astrophysics, equation-of-state studies and fusion energy research. Laser-driven implosions of spherical polymer shells have, for example, achieved an increase in density of 1,000 times relative to the solid state. These densities are large enough to enable controlled fusion, but to achieve energy gain a small volume of compressed fuel (known as the 'spark') must be heated to temperatures of about 108 K (corresponding to thermal energies in excess of 10 keV). In the conventional approach to controlled fusion, the spark is both produced and heated by accurately timed shock waves, but this process requires both precise implosion symmetry and a very large drive energy. In principle, these requirements can be significantly relaxed by performing the compression and fast heating separately; however, this 'fast ignitor' approach also suffers drawbacks, such as propagation losses and deflection of the ultra-intense laser pulse by the plasma surrounding the compressed fuel. Here we employ a new compression geometry that eliminates these problems; we combine production of compressed matter in a laser-driven implosion with picosecond-fast heating by a laser pulse timed to coincide with the peak compression. Our approach therefore permits efficient compression and heating to be carried out simultaneously, providing a route to efficient fusion energy production.     

A high-intensity highly coherent soft X-ray femtosecond laser seeded by a high harmonic beam

Synchrotrons have for decades provided invaluable sources of soft X-rays, the application of which has led to significant progress in many areas of science and technology. But future applications of soft X-rays--in structural biology, for example--anticipate the need for pulses with much shorter duration (femtoseconds) and much higher energy (millijoules) than those delivered by synchrotrons. Soft X-ray free-electron lasers should fulfil these requirements but will be limited in number; the pressure on beamtime is therefore likely to be considerable. Laser-driven soft X-ray sources offer a comparatively inexpensive and widely available alternative, but have encountered practical bottlenecks in the quest for high intensities. Here we establish and characterize a soft X-ray laser chain that shows how these bottlenecks can in principle be overcome. By combining the high optical quality available from high-harmonic laser sources (as a seed beam) with a highly energetic soft X-ray laser plasma amplifier, we produce a tabletop soft X-ray femtosecond laser operating at 10 Hz and exhibiting full saturation, high energy, high coherence and full polarization. This technique should be readily applicable on all existing laser-driven soft X-ray facilities.     

基于CRUISE的PHEV控制策略参数仿真

并联式混合动力电动汽车（PHEC）通过恰当的控制策略使内燃机动力源和电力动力源协调配合,实现最佳能量分配,既能保持电动汽车超低排放的优点,又能发挥传统内燃机汽车高比能量的长处．运用CRUISE软件建立了仿真模型,设计了并联电助力式控制策略,利用建立的仿真软件进行了控制策略及控制参数的仿真研究．仿真结果表明,根据不同的控制要求,调整相应的控制参数,可以改善整车性能．     

基于信任云的簇化层次式WSN安全路由方法

如何能量高效地保障无线传感网的路由安全一直是一个巨大的挑战。提出一种基于信任云的簇化层次式无线传感网安全路由算法(trusted cloud-based secure routing algorithm,TC-SRA),建立基于信任云的无线传感网安全骨架,通过簇化层次式拓扑实现网络节点的高效管理,从兼顾能效和安全的角度提升无线传感网的路由性能。仿真测试结果表明,所提出的算法不仅为无线传感网的路由安全实现提供了新思路,而且能有效控制网络节点的能耗,保障网络生命周期。     

Efficient Algorithm for Energy-Aware Virtual Network Embedding

Network virtualization is a promising approach for resource management that allows customized Virtual Networks(VNs) to be multiplexed on a shared physical infrastructure. A key function that network virtualization can provide is Virtual Network Embedding(VNE), which maps virtual networks requested by users to a shared substrate network maintained by an Internet service provider. Existing research has worked on this, but has primarily focused on maximizing the revenue of the Internet service provider. In this paper, we consider energy-aware virtual network embedding, which aims at minimizing the energy consumption for embedding virtual networks in a substrate network. In our optimization model, we consider energy consumption of both links and nodes. We propose an efficient heuristic to assign virtual nodes to appropriate substrate nodes based on priority, where existing activated nodes have higher priority for hosting newly arrived virtual nodes. In addition, our proposed algorithm can take advantage of activated links for embedding virtual links so as to minimize total energy consumption. The simulation results show that, for all the cases considered, our algorithm can improve upon previous work by an average of12.6% on acceptance rate, while the consumed energy can be reduced by 12.34% on average.     

An Energy-Aware Routing Protocol Based on Effective Transmission in Sensor Networks

In order to minimize the energy consumption in the discovery of the routing path, this paper introduces a novel concept of effective transmission （ET） that ensures each forwarding node is not only farther from the source node, but also nearer to the destination node with respect to its sender, An energ-aware routing protocol based on ET is proposed. It enables the energy consumption for each hop to be the least for the transmission. The simulation results show the routing protocol is effective in the performance of energy consumption comparing with some other routing protocols.     

D+OH (A2∑+,v=0，j=0)的反应动力学

在用多体项展式方法建立HDO分子解析势能函数的基础上,用准经典轨线（Quasiclassical trajectory, QCT）方法,研究了碰撞体系D+OH (〖WTBX〗A2∑+, v=0, j=0)在5个产物通道上的动力学特点. 结果表明：即使碰撞能量较低, D+OH (A2∑+,v=0, j=0)也不能形成长寿命络合物;交换反应D+OH→DH+O和D+OH→DO+H能在较宽的碰撞能量范围内发生, 且均为无阈能的放热反应,但其发生的几率不同,前者的反应截面明显大于后者;当碰撞能量进一步增大时（例如     

崇明生态岛可再生能源产业发展路径分析

崇明岛是世界上最大的河口冲积岛,发展目标定位于世界级生态岛,受到国内外的诸多关注.提出一种产业发展的集成分析方法,将态势分析法(SWOT)和钻石模型结合起来研究在崇明岛发展可再生能源产业的可行性.结果表明:①短期内崇明岛可再生能源产业难以出现较大的发展,但远期有可能成为崇明世界级生态岛经济建设中的重要产业;②应注重"错位发展",选择适合崇明岛特点的可再生能源产业细分市场;③崇明岛可再生能源产业发展具有良好的外部环境和较强的需求;④崇明岛在生产要素和相关行业支撑方面十分薄弱,也缺乏明确的战略,因而竞争力有限;⑤可再生能源产业具有高增长的特性,可以带给崇明岛较大的后发优势,但如果想要实现这种后发优势,必须充分发挥政策优势和外部力量的作用.     

Nonlinear optics in the extreme ultraviolet

Nonlinear responses to an optical field are universal in nature but have been difficult to observe in the extreme ultraviolet (XUV) and soft X-ray regions owing to a lack of coherent intense light sources. High harmonic generation is a well-known nonlinear optical phenomenon and is now drawing much attention in attosecond pulse generation. For the application of high harmonics to nonlinear optics in the XUV and soft X-ray regime, optical pulses should have both large pulse energy and short pulse duration to achieve a high optical electric field. Here we show the generation of intense isolated pulses from a single harmonic (photon energy 27.9 eV) by using a sub-10-femtosecond blue laser pulse, producing a large dipole moment at the relatively low (ninth) harmonic order nonadiabatically. The XUV pulses with pulse durations of 950 attoseconds and 1.3 femtoseconds were characterized by an autocorrelation technique, based on two-photon above-threshold ionization of helium atoms. Because of the small cross-section for above-threshold ionization, such an autocorrelation measurement of XUV pulses with photon energy larger than the ionization energy of helium has not hitherto been demonstrated. The technique can be extended to the characterization of higher harmonics at shorter wavelengths.     

并联式混合动力汽车机械式自动变速器换档策略

并联式混合动力汽车(Parallel Hybrid Electric Vehicle,PHEV)档位决策作为能量管理策略的一部分,对整车动力性、经济性及排放性能有较大影响.混合动力汽车换档策略不仅要考虑发动机,还要考虑电机和电池系统的影响.基于电池电能的等效燃油概念,通过考虑电池充、放电过程中的能量损失,将充、放电生成或消耗的电能折算为等效燃油,由此得到不同档位时整车的综合燃油消耗,进而选取燃油消耗较小时的档位使整车经济性能指标达到最优.同时,该方法也通用于装备液力自动变速器(Automatic Transmission,AT)等有级式自动变速器的混合动力汽车换档策略制定.     

两体关联核物质结合能的计算

在量子强子动力学（ＱＨＤ）框架中采用Ｗａｌｅｃｋａ模型计算了两体关联核物质中的结合能。在此模型中,核子之间的相互作用通过标量介子（σ）和矢量介子（ω）的交换而产生,其中的近似包括了一个自洽的相对论的“梯形”图的和,体系的一部分对自由空间的ＮＮ问题作了发展。其结论是,关联对于核子自能有一个较小的影响,但对于结合能产生了一个有意义的改变。     

地下洞室群开挖顺序优化设计

遵循动态规划原理建立了地下洞室群开挖顺序动态规划模型,提出了评价不同开挖排序方案优劣的最小能量偏差准则,并以能量偏差为目标函数.实例计算表明,开挖顺序对围岩稳定的影响是明显的,对开挖顺序的优化要给予重视;提出的地下洞室群开挖顺序动态规划模型合理,计算工作量较少;以形状改变比能偏差为目标函数的优化方案中最大洞周位移比位移类目标函数的最大洞周位移略大,但从应力状态、塑性区面积和能量的角度考虑,前者的优化方案更佳.因此,以形状改变比能偏差为目标函数更合理.     

The role of autophagy during the early neonatal starvation period

At birth the trans-placental nutrient supply is suddenly interrupted, and neonates face severe starvation until supply can be restored through milk nutrients. Here, we show that neonates adapt to this adverse circumstance by inducing autophagy. Autophagy is the primary means for the degradation of cytoplasmic constituents within lysosomes. The level of autophagy in mice remains low during embryogenesis; however, autophagy is immediately upregulated in various tissues after birth and is maintained at high levels for 3-12 h before returning to basal levels within 1-2 days. Mice deficient for Atg5, which is essential for autophagosome formation, appear almost normal at birth but die within 1 day of delivery. The survival time of starved Atg5-deficient neonates (approximately 12 h) is much shorter than that of wild-type mice (approximately 21 h) but can be prolonged by forced milk feeding. Atg5-deficient neonates exhibit reduced amino acid concentrations in plasma and tissues, and display signs of energy depletion. These results suggest that the production of amino acids by autophagic degradation of 'self' proteins, which allows for the maintenance of energy homeostasis, is important for survival during neonatal starvation.     

Low-complexity energy-aware sensor selection for noise reduction in distributed microphone networks

Noise reduction (NR) is a necessary front-end in many audio applications for improving signal quality. It was shown that sparsity-promoting sensor selection potentially makes a trade-off between energy consumption and NR performance, which is rather important for large-scale wireless acoustic sensor networks (WASNs), where many sensors contribute negligibly to NR but energy consumption affects the lifetime of WASNs. This paper presents a sensor selection approach for beamforming-based NR by minimizing the total energy consumption and constraining the output noise variance. Motivated by the optimal semi-definite programming (SDP) solution and the utility-based method, we propose three low-complexity selection metrics: weighted utility, gradient, and weighted input signal-to-noise ratio (SNR). It is shown that the proposed weighted utility and gradient-based methods are near-optimal in performance but much faster than the SDP-based method, and the weighted SNR method has the lowest time complexity with a tiny performance sacrifice. Numerical results using a simulated WASN validate the superiority of the proposed approaches over conventional methods.     

用SEA法研究板及加筋板的隔声量

本文对广泛用于工程结构的板和加筋板的隔声量进行了研究。通过对同样声载作用、不同频段的板和加筋板隔声量的实测值和计算值的比较,发现加筋板的隔声量在低频域比板的大,在高频域则相反。本文用统计能量分析的方法,从板和加筋板的能量平衡方程式出发,解释了这一用质量定律不能解释的现象。