氨吸收式串联型动力/制冷复合循环

本文提出了一种新型的采用氨水混合工质的动力／制冷复合循环,该循环以中低温工业余热或燃气轮机排气为热源,将动力、制冷子循环采用串联方式连接,基础循环工质为氨质量浓度为0．27的氨水溶液,热源为365℃／104．3 kPa 的热空气,透平进气参数为350℃／3750 kPa,,以热效率η1、(火用)效率η2作为评价准则,模拟计算表明本循环的热效率η1 为17．8％,炯效率η2为45％,通过与其它有代表性的分供系统及联供系统进行热力性能方面的比较,表明本循环η1、η2均有不同程度提高。     

Study of three rotating radio transients with FAST

Rotating radio transients(RRATs) are peculiar astronomical objects whose emission mechanism remains under investigation.In this paper, we present observations of three RRATs, J1538+2345, J1854+0306 and J1913+1330, carried out with the Fivehundred-meter Aperture Spherical radio Telescope(FAST). Specifically, we analyze the mean pulse profiles and temporal flux density evolutions of the RRATs. Owing to the high sensitivity of FAST, the derived burst rates of the three RRATs are higher than those in previous reports. RRAT J1854+0306 exhibited a time-dynamic mean pulse profile, whereas RRAT J1913+1330 showed distinct radiation and nulling segments on its pulse intensity trains. The mean pulse profile variation with frequency is also studied for RRAT J1538+2345 and RRAT J1913+1330, and the profiles at different frequencies could be well fitted with a cone-core model and a conal-beam model, respectively.     

有机半导体的物理掺杂理论

基于最低未被占据分子轨道（LUMO）和最高被占据分子轨道（HOMO）的高斯态密度分布与载流子在允许量子态中的费米-狄拉克（Fermi-Dirac）分布,提出有机半导体中物理掺杂的理论模型;研究了掺杂浓度、温度和禁带宽度对载流子浓度的影响,并与一些报道的实验结果做了比较.研究发现无论是否掺杂,温度升高时,有机半导体中的载流子浓度都会增大,并且随温度倒数的线性减小而指数增大;对于本征有机半导体,载流子浓度随禁带宽度的增大而指数下降,随高斯分布宽度的平方指数增加;对杂质和主体不同能级关系的掺杂情形下掺杂浓度对载 关键词： 有机半导体 掺杂 高斯态密度 载流子浓度     

Experimental and numerical investigation of a stagnation pulverised coal flame

A multi-stream Flamelet Progress Variable (FPV) model, specifically developed for coal combustion, is proposed. The model accounts for the different fuel streams associated with the volatile and char burnout products. The applicability of the new FPV model is investigated in a laminar stagnation pulverized coal flame. The flame considered is a premixed mixture of CH₄, O₂ and N₂, carrying pulverized coal particles, stabilized in an impinging wall. Spontaneous emissions of OH*, CH* and C${}_2^{*}$ are measured to identify the flame. The 1D numerical simulations of the experimental conditions are able to reproduce the main features of the flame. The applicability of the multi-stream FPV model to coal combustion is further evaluated with the a posteriori analysis of the FPV results, comparing the results with a reference model, where the species are fully transported and the chemistry directly evaluated. Then, with the budget analysis, the influence of the control variables used to build the look-up table is assessed by examining the conditional contributions to the overall transport terms of scalar quantities (e.g. species, temperature). The results of both analyses show that the proposed multi-stream FPV model can accurately predict the main features of coal combustion, with only minor issues related to the manifold used to build the look-up table.     

Bipartite entanglement of a two-qubit system with anisotropic couplings under nonuniform magnetic fields

This paper investigates bipartite entanglement of a two-qubit system with anisotropic couplings under an inhomogeneous magnetic field. This work is mainly to investigate the characteristics of a Heisenberg XYZ chain and obtains some meaningful results. By the concept of negativity, it finds that the inhomogeneity of magnetic field may induce entanglement and the critical magnetic field is independent of J_z. The inhomogeneous magnetic field can increase the value of critical magnetic field B_c. It also finds that the magnetic field not only suppresses the entanglement but also can induce it to revival for some time.     

双球聚集粒子辐射特性分析

基于广义Mie理论求解方法(GMM),考虑单元粒子之间的相互作用,计算了不同尺度参数不同间距的双球聚集粒子的衰减因子、散射因子等辐射特性参数,同时分析了双球聚集粒子与不考虑相互作用计算所得的辐射特性差异,分析结果表明:考虑相互作用与不考虑相互作用计算所得的双球聚集粒子的辐射特性存在着一定的差别,这种差别随粒子间距、尺度参数的变化而变化,最大偏差达30%左右.     

不可微规划的极大熵不动点算法

本文将极大熵逼近方法和不动点计算方法有机地结合,提出了一种不可微规划计算方法．该方法同样也适用于求解可微规划,而后给出了该方法的收敛性     

Combinatorial coverings from geometries over principal ideal rings

A t-(v, k, λ) covering is an incidence structure with v points, each block incident on exactly k points, such that every set of t distinct points is incident on at least λ blocks. By considering certain geometries over finite principal ideal rings, we construct infinite families of t-(v, k, λ) coverings having many interesting combinatorial properties. © 1999 John & Sons, Inc. J Combin Designs 7: 247–268, 1999