Competitive insurance pricing with complete information,loss-averse utility and finitely many policies

In a recent paper, Ramsay and Oguledo (2012) show that in a competitive insurance market with complete information about individuals’ accident probabilities and production costs, which are proportional to the amount of insurance purchased and to the premium charged, only individuals whose accident probability is in a medium range are insurable and desire insurance. The purpose of this paper is to complement the analysis of Ramsay and Oguledo by considering production costs which are proportional to the number of policies offered by an insurer. In addition to the result of Ramsay and Oguledo we show that the group of individuals who obtain insurance is partitioned into several subgroups, where each subgroup is offered the same insurance policy. To derive this result we introduce the concept of incentive compatibility which ensures that an individual has no incentive to buy another policy. Assuming that individuals have loss-averse utility, we fully characterize the boundaries of these subgroups as the result of an undercutting process in premiums between the insurers.     

The loss given default of a low-default portfolio with weak contagion

In this paper we study the loss given default (LGD) of a low default portfolio (LDP), assuming that there is weak credit contagion among the obligors. We characterize the credit contagion by a Sarmanov dependence structure of the risk factors that drive the obligors’ default, where the risk factors are assumed to be heavy tailed. From a new perspective of asymptotic analysis, we derive a limiting distribution for the LGD. As a consequence, an approximation for the entire distribution, in contrast to just the tail behavior, of the LGD is obtained. We show numerical examples to demonstrate the limiting distribution. We also discuss possible applications of the limiting distribution to the calculation of moments and the Value at Risk (VaR) of the LGD.     

来流特性对高速扩压叶栅端壁射流旋涡的影响

在进口马赫数Ma=0.67的高速平面扩压叶栅上,开展了不同来流附面层厚度和湍流强度对端壁射流旋涡发生器控制效果的影响研究。结果表明,与来流湍流强度相比,进口附面层厚度对栅内流动的影响更大,随着其厚度的增加,栅内二次流动增强,损失增大;来流湍流强度对叶栅气动性能的影响减弱。射流旋涡在较小附面层厚度条件下减小栅内损失的效果随着湍流强度的增加而减弱,甚至会恶化其气动性能;而当附面厚度较大时,射流穿透能力减弱,湍流强度的增大将减小射流旋涡上洗区掺混损失并减缓其下洗侧与吸力面间端壁附面层的发展,叶栅气动性能的提高更加显著。当δ=15%H、T_u=10%时,射流旋涡使得栅内损失减小达8.4%。     

Cut-off frequency of magnetostrictive materials based on permeability spectra

The loss behavior and cut-off frequency of TbDyFe alloy and TbDyFe/epoxy composite have been investigated by measuring their permeability spectra. The loss factor of TbDyFe alloy increases exponentially as the frequency goes up, while it is almost unchanged for the TbDyFe/epoxy composite. The loss factor value for the TbDyFe composite is only 4.3% of that for the monolithic TbDyFe alloy at high frequency of 10 kHz under the peak magnetic induction of 10 mT. The cut-off frequency of TbDyFe/epoxy composite is 6800 kHz, 3 orders of magnitude larger than that of TbDyFe alloy. The cut-off frequency is found to be the ferromagnetic resonance frequency and can be calculated from Snoek's law.     

Influence of composition of carbonyl iron particles on dynamic mechanical properties of magnetorheological elastomers

Magnetorheological elastomers (MRE) are known as smart materials. However, the magnetorheological (MR) effect of MRE is not high enough at present, which limits its engineering applications. Prior studies have shown that magneto-induced shear storage modulus and MR effect were mainly determined by the performance of the ferromagnetic particles. In this paper, MRE samples were prepared by carbonyl iron particles (CIP) of different compositions based on silicon rubber under external magnetic field. Their microstructures were observed using an optical digital microscope and a scanning electron microscope. The dynamic mechanical properties of MRE samples were measured using a modified dynamic mechanical analyzer under varying magnetic field strength and frequency. The results show that the carbon content of CIP have a greater impact on the dynamic mechanical properties of MRE. The magneto-induced shear storage modulus and MR effect can be increased by selecting CIP of low carbon content. In addition, the damping property is also significantly influenced by the carbon content of the CIP. This study is expected to provide guidance for fabrication of high performance MRE.     

引射式气帘对COIL流场参数的影响

 给出了氧碘化学激光器中,引射式气帘对激光器内各段压力与输出功率等参数的影响。研究结果表明：在COIL光腔中采用引射式气帘的作用方式,可以显著降低光腔段的总压损失,为激光器后的压力恢复系统减轻工作负荷;在高背压条件下,能够显著降低腔压,改善光腔静压的稳定性,提高激光器输出功率的稳定性。     

Development and Verification of a Diagnostic Technology for Waste Battery Deterioration Factors

We defined four major deterioration factors (electrolyte loss (EL), lithium loss (LL), lithium precipitation (LP), and compound deterioration (CD)). Then, we derived eleven key performance indicators (KPIs) for comparative analysis. After that, we fabricated three deteriorated cells for each of three deterioration factors (EL, LL, and LP) and one cell with CD (for verification) with four individual (dis)charging experiment manuals. The two major contributions of this study are the performance of 1) trend analysis to determine a suitable diagnostic metric by inspecting the eleven KPIs and 2) comparison analysis of and to verify the effectiveness of utilizing as a real-time deterioration diagnostic factor using a concept of model-in-the-loop simulation. The results show that 1) has the most conspicuous trendline tendency among the eleven comparison targets for all four major deterioration factors, and 2) the angle difference between the two trends of and lies within a minimum of 9° and a maximum of 43° (with a sscale on the x-axis and a scale on the y-axis for a clear trend line analysis). From this, we can conclude that the trendline-based real-time deterioration analysis employing may be practically applicable to a limited extent.     

基于优化YOLOv5s的老人跌倒检测算法

针对跌倒对老年人安全性问题造成的影响，以及现有目标检测模型在人物跌倒时易漏检、鲁棒性和泛化能力差等问题，对YOLOv5s算法进行优化，提出一种老人跌倒检测算法。使用改进的RepVGG模块代替YOLOv5s算法中的3×3卷积模块，优化损失函数，选择K-means++算法对所用数据集进行聚类优化。结果表明，所提算法的鲁棒性好、泛化能力强，平均准确率比YOLOv3,YOLOv4,YOLOv5s, CBAM-YOLOv5s模型分别提高了9%,8%,3%和1.2%。所提出的算法能够满足现实中不同场景对老人跌倒行为的检测需求，可以应用于移动设备或者监控设备中，在老年人安全保障领域发挥重要作用。     

Impact of Electrostatic Interaction on Non-radiative Recombination Energy Losses in Organic Solar Cells Based on Asymmetric Acceptors

Reducing non-radiative recombination energy loss (ΔE₃) is one key to boosting the efficiency of organic solar cells. Although the recent studies have indicated that the Y-series asymmetric acceptors-based devices featured relatively low ΔE₃, the understanding of the energy loss mechanism derived from molecular structure change is still lagging behind. Herein, two asymmetric acceptors named BTP-Cl and BTP-2Cl with different terminals were synthesized to make a clear comparative study with the symmetric acceptor BTP-0Cl. Our results suggest that asymmetric acceptors exhibit a larger difference of electrostatic potential (ESP) in terminals and semi-molecular dipole moment, which contributes to form a stronger π–π interaction. Besides, the experimental and theoretical studies reveal that a lower ESP-induced intermolecular interaction can reduce the distribution of PM6 near the interface to enhance the built-in potential and decrease the charge transfer state ratio for asymmetric acceptors. Therefore, the devices achieve a higher exciton dissociation efficiency and lower ΔE₃. This work establishes a structure-performance relationship and provides a new perspective to understand the state-of-the-art asymmetric acceptors.