托卡马克中局域磁扰动引起的高能量离子损失研究

基于单粒子导心运动代码ORBIT，采用测试粒子模拟方法，研究了托卡马克等离子体内部不同径向位置处局域磁场扰动对高能量离子的损失的影响。研究表明，在局域磁扰动主要分布在某磁面附近、其环向具有类似纹波场形式下，可造成一些靠近等离子体中心区域的高能量离子损失，但对靠近等离子边界的离子损失影响相对不大。这些损失的高能量离子均为捕获离子，离子的投掷角越大就越容易损失。此外，造成高能量离子最大损失率的局域场径向位置与这些损失离子的初始径向位置通常存在一定的偏移，而且这个偏移与这些离子的能量密切相关。当局域场出现在某些位置时，能量较低的离子会有一定的损失，能量较高的离子反而不会损失。     

An antimonene modified hole extraction layer for high efficiency PEDOT:PSS-free nonfullerene organic solar cells

In this paper, a bilayer hole extraction layer (HEL) with solution-processed molybdenum trioxide (MoO₃) and two-dimensional (2D) material of antimonene was developed to achieve high performance nonfullerene organic solar cells (NF–OSCs). The application of antimonene facilitates effective charge extraction and lowered recombination loss, achieving improved photovoltaic performance. By inserting the antimonene layer, power conversion efficiency (PCE) of devices with MoO₃ HEL was increased from 8.92% to 11.30% in OSCs with non-fullerene systems of PBDB-T-2F:IT-4F, which was even much higher than that of the devices with PEDOT:PSS HEL (10.59%). Results make it clear that the solution-processed bilayer MoO₃/antimonene HEL shows great potential for application in high performance PEDOT:PSS-free NF–OSCs.     

Indirect test of M-S circuits using multiple specification band guarding

Testing analog and mixed-signal circuits is a costly task due to the required test time targets and high end technical resources. Indirect testing methods partially address these issues providing an efficient solution using easy to measure CUT information that correlates with circuit performances. In this work, a multiple specification band guarding technique is proposed as a method to achieve a test target of misclassified circuits. The acceptance/rejection test regions are encoded using octrees in the measurement space, where the band guarding factors precisely tune the test decision boundary according to the required test yield targets. The generated octree data structure serves to cluster the forthcoming circuits in the production testing phase by solely relying on indirect measurements. The combined use of octree based encoding and multiple specification band guarding makes the testing procedure fast, efficient and highly tunable. The proposed band guarding methodology has been applied to test a band-pass Butterworth filter under parametric variations. Promising simulation results are reported showing remarkable improvements when the multiple specification band guarding criterion is used.     

A model to estimate the path loss in areas with foliage of trees

This paper presents an empirical model to predict attenuation in forest environments considering parameters related to vegetation. Typically, environmental parameters are only included in theoretical models, but they are more difficult to apply. The developed model uses tree density, average tree canopy diameter and foliage density as input parameters. The foliage density is very difficult to determine since it depends on the characteristics of trees. A simple metric of this parameter was obtained by measuring the background light silhouetted by the canopy. The model was developed with measurements obtained in different forest environments for two frequencies within the UHF band (Ultra High Frequency). A procedure was also applied to extend the operating frequency range of the model.     

The (S−1,S) inventory model and its counterparts in queueing theory

We explore the relationship between the ($S?1,S$) inventory model and three well-known queueing models: the Erlang loss system, the machine-repair model and a two-node Jackson network. Exploiting this relationship allows us to obtain key performance measures of the ($S?1,S$) model, like the so-called virtual outdating time, the number of items on the shelf in steady state, the long-run rate of unsatisfied demands and the distribution of the empty shelf period.     

Flamelet structure in turbulent premixed swirling oxy-combustion of methane

Two key flame macrostructures in swirling flows have been observed in experiments of oxy-combustion (as well as air-combustion); as the equivalence ratio is raised, the flame moves from being stabilized on just the inner shear layer (Flame III) to getting stabilized on both the inner and outer shear layers (Flame IV). We report results of an LES investigation of two different inlet oxy-fuel mixtures, in a turbulent swirling flow at $\text{Re}=20,000,$ that capture these two macrostructures. Previous work on the effects of heat loss have mostly focused on its impact on macro-scale observations. In this paper, we examine how heat loss impacts the flame microstructures as well for these two macrostructures. For both flames, the flamelet structure, as represented by a scatter plot of the normalized fuel concentration against the normalized temperature, depends on whether the combustor walls are adiabatic or non-adiabatic. For the adiabatic case, the flamelets of both macrostructures behave like strained flames. When wall heat transfer is included, Flame III microstructure is more bimodal. Since this flame extends farther downstream and part of it propagates along the walls, heat transfer has a greater impact on it’s microstructure. These results show that heat loss impacts not just the macro properties of the flame such as its shape or interactions with the wall, but also fundamentally changes its internal structure. Scatter plots of the turbulent flames are constructed and compared to different 1D laminar flame profiles (e.g., strained or with heat loss), and comparisons suggest the important role of the wall thermal boundary conditions in the accurate simulations of combustion dynamics and interpretations of experimental data, including data reduction and scaling.     

Irreversible Structural Changes of Copper Hexacyanoferrate Used as a Cathode in Zn-Ion Batteries

The structural changes of copper hexacyanoferrate (CuHCF), a Prussian blue analogue, which occur when used as a cathode in an aqueous Zn-ion battery, are investigated using electron microscopy techniques. The evolution of Zn_xCu_1−xHCF phases possessing wire and cubic morphologies from initial CuHCF nanoparticles are monitored after hundreds of cycles. Irreversible introduction of Zn ions to CuHCF is revealed locally using scanning transmission electron microscopy. A substitution mechanism is proposed to explain the increasing Zn content within the cathode material while simultaneously the Cu content is lowered during Zn-ion battery cycling. The present study demonstrates that the irreversible introduction of Zn ions is responsible for the decreasing Zn ion capacity of the CuHCF cathode in high electrolyte concentration.     

Spectral,Optical and Mechanical studies on pure and thiourea doped ammonium di-hydrogen phosphate NLO single crystals

Pure and thiourea substituted single crystals of ammonium di-hydrogen phosphate have been grown from aqueous solution by isothermal solvent evaporation technique. Doped crystal exhibits prominent changes in physical and chemical properties. Single crystal XRD analyses of the samples are carried out and the results are compared. FTIR and UV–vis–NIR spectral analyses have been employed to identify the presence of various functional groups and the UV cut-off range in the grown crystals. Density measurements have been made and Photoconductivity studies revealed the negative photo conducting nature. Hardness measurement shows that the mechanical strength of the doped crystal is high when compared to pure ammonium di-hydrogen phosphate. The dielectric response of the samples has been studied in the frequency range 100 Hz–5 MHz at room temperature and the results are discussed.     

Packet loss visibility across SD,HD, 3D,and UHD video streams

The trend towards video streaming with increased spatial resolutions and dimensions, SD, HD, 3D, and 4kUHD, even for portable devices has important implications for displayed video quality. There is an interplay between packetization, packet loss visibility, choice of codec, and viewing conditions, which implies that prior studies at lower resolutions may not be as relevant. This paper presents two sets of experiments, the one at a Variable BitRate (VBR) and the other at a Constant BitRate (CBR), which highlight different aspects of the interpretation. The latter experiments also compare and contrast encoding with either an H.264 or an High Efficiency Video Coding (HEVC) codec, with all results recorded as objective Mean Opinion Score (MOS). The video quality assessments will be of interest to those considering: the bitrates and expected quality in error-prone environments; or, in fact, whether to use a reliable transport protocol to prevent all errors, at a cost in jitter and latency, rather than tolerate low levels of packet errors.     

Study on properties of flame‐retardant cyanate esters modified with DOPO and triazine compounds

Ternary flame‐retardant modified cyanate ester blends (CEPG and CEPA) are formed by combining triazine compounds (TGIC or TAIC) and 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide with cyanate ester resin. The curing behaviors, thermal and mechanical properties, and the flame‐retardant properties are investigated. The results show that the CEPG and CEPA blends result in lower curing temperatures and glass transition temperatures than those of neat CE. Both of CEPG and CEPA blends significantly improve the flame‐retardant properties of CE resins, and UL‐94V‐0 rate is achieved for CEPG‐1.0 and CEPA‐0.5. The dielectric constant and loss of CEPA blends are lower than those of CEPG blend with the same phosphors content, and both of them are lower than those of neat CE. Therefore, the ternary flame‐retardant modified cyanate ester blends provide 2 ways for composites of producing printed circuit board with high flame‐retardant property and low dielectric constant and loss.