An examination of the efficiency of the marketing distribution channel and organizational structure for insurance companies is presented from a framework that views the insurer as a financial intermediary rather than as a "production entity" which produces "value added" through loss payments. Within this financial intermediary approach, solvency can be a primary concern for regulators of insurance companies, claims-paying ability can be a primary concern for policyholders, and return on investment can be a primary concern for investors. These three variables (solvency, financial return, and claims-paying ability) are considered as outputs of the insurance firm. The financial intermediary approach acknowledges that interests potentially conflict, and the strategic decision makers for the firm must balance one concern versus another when managing the insurance company. Accordingly, we investigate the efficiency of insurance companies using data envelopment analysis (DEA) having as insurer output an appropriately selected (for the firm under investigation) combination of solvency, claims-paying ability, and return on investment as outputs. These efficiency evaluations are further examined to study stock versus mutual form of organizational structure and agency versus direct marketing arrangements, which are examined separately and in combination. Comparisons with the "value-added" or "production" approach to insurer efficiency are presented. A new DEA approach and interpretation is also presented. Copyright The Journal of Risk and Insurance.

The time evolution of dielectric barrier discharge driven by nanosecond pulse high-voltage power is investigated by high-speed video analysis, electrical measurements and spectral diagnostics. It is found that the discharge mode generally goes through the evolution process of filamentary discharge → diffuse discharge → filamentary discharge with the increase in discharge cycle. The time-dependent changes in the standard deviation of image gray levels indicate that the discharge uniformity first improves and then deteriorates in this evolution process. The different pre-ionization density and modulated distribution of space charges and surface charges are considered to be the main reasons for the time evolution of discharge uniformity. In addition, the experiments under different frequencies and voltages show that the transition of the discharge mode is more likely to occur at higher frequency and higher voltage. Further measurement and calculation reveal that the discharge at high frequency and high voltage has the same characteristics, that is, high pre-ionization degree, thick filament diameter and short time lag. These characteristics usually lead to higher seed electron density, larger critical avalanche size and weaker lateral inhibition effect, which make the discharge mode transition more likely to occur.

A magnetic field, with the direction parallel to the electric field, is applied to the repetitively unipolar positive nanosecond pulsed dielectric barrier discharge. The effect of the parallel magnetic field on the plasma generated between two parallel-plate electrodes in quiescent air is experimentally studied under different pulse repetition frequencies (PRFs). It is indicated that only the current pulse in the rising front of the voltage pulse occurs, and the value of the current is increased by the parallel magnetic field under different PRFs. The discharge uniformity is improved with the decrease in PRF, and this phenomenon is also observed in the discharge with the parallel magnetic field. By using the line-ratio technique of optical emission spectra, it is found that the average electron density and electron temperature under the considered PRFs are both increased when the parallel magnetic field is applied. The incremental degree of average electron density is basically the same under the considered PRFs, while the incremental degree of electron temperature under the higher-PRFs is larger than that under the lower-PRFs. All the above phenomena are explained by the effect of parallel magnetic field on diffusion and dissipation of electrons.

The effect of flowing air on dielectric barrier discharge excited by alternating voltage was investigated by high-speed video analysis and electrical measurements. The discharge was still in filamentary mode in flowing air, and the space-time distribution of filaments was changed by airflow. With the increase in airflow velocity, the space-time distribution of discharge filaments shown in top view images went through four phases, that is, spot-like distribution, line-like distribution, cotton-like distribution, and stripe-like distribution. Accordingly, the motion and morphology of discharge filaments shown in side view images also presented four phases: remaining still and straight between adjacent cycles, moving and bending downstream, almost remaining still and straight between adjacent cycles, and moving and bending downstream again. Different motions of filaments were considered to be the reason for the changed distribution of filaments in flowing air. In addition, the intensity of discharge in flowing air was enhanced by increasing the gas gap and discharge frequency. At high discharge current, larger airflow velocity was needed to reach phase transition. The changed distribution of micro-discharge remnants in flowing air can be responsible for the phase transition. Micro-discharge remnants redistributed during the time interval of adjacent half-cycle discharges, under the action of various forces, such as electric field force, drag force, repulsive force, electrostatic coupling force, and trap binding force. The changed position of micro-discharge remnants led to the complex motions of discharge filaments and further resulted in the changed space-time distribution of filaments.

No abstract

Abstract. Liquid water in aerosol particles has a significant effect on their optical properties, especially on light scattering, whose dependence on chemical composition is investigated here using measurements made in southern Beijing in 2019. The effect is measured by the particle light scattering enhancement f(RH), where RH denotes the relative humidity, which is found to be positively and negatively impacted by the proportions of inorganic and organic matter, respectively. Black carbon is also negatively correlated. The positive impact is more robust when the inorganic matter mass fraction was smaller than 40 % (R=0.93, R: the Pearson's correlation coefficient), becoming weaker as the inorganic matter mass fraction gets larger (R=0.48). A similar pattern was also found for the negative impact of the organic matter mass fraction. Nitrate played a more significant role in aerosol hygroscopicity than sulfate in Beijing. However, the deliquescence point of ambient aerosols was at about RH = 80 % when the ratio of the sulfate mass concentration to the nitrate mass concentration of the aerosol was high (mostly higher than ∼ 4). Two schemes to parameterize f(RH) were developed to account for the deliquescent and non-deliquescent effects. Using only one f(RH) parameterization scheme to fit all f(RH) processes incurs large errors. A piecewise parameterization scheme is proposed, which can better describe deliquescence and reduces uncertainties in simulating aerosol hygroscopicity.

Diffuse discharges excited by unipolar positive and bipolar pulses can be achieved by a self-designed dielectric barrier discharge (DBD) structure (a metal rod is inserted into a traditional parallel-plate DBD structure) exposed in airflow. For a self-designed DBD excited by unipolar positive pulses, only a primary discharge occurs in a voltage pulse. When the applied voltage is low, a diffuse discharge first appears near the anode. As the voltage further increases, a diffuse discharge appears in a larger area near the anode. Until the applied voltage is high enough, the discharge fills the whole discharge gap. Additionally, there is a priority region around the metal rod for the development of a diffuse discharge. However, for a self-designed DBD excited by bipolar pulses, two separate discharges are observed in a voltage pulse. The primary discharge occurs at the rising front of the voltage pulse, and the secondary discharge (reverse discharge) takes place at the falling front of the voltage pulse. When the applied voltage is low, the diffuse discharge first starts from the priority region around the metal rod placed in the center of the discharge electrode. As the voltage further increases, the diffuse discharge appears in a larger area around the metal rod. The above observations about the different spatial evolutions of diffuse discharge areas excited by unipolar positive and bipolar pulses are mainly ascribed to the difference of a strong local electric field caused by residual charges. This diffuse discharge has potential applications in surface treatment of materials and thin film deposition.

An experimental study of the effects of airflow, magnetic field, and combination of airflow with magnetic field on a nanosecond pulsed dielectric barrier discharge (DBD) in atmospheric air is presented. The DBD is generated by an in-house designed DBD structure (a metal rod is inserted into the traditional parallel-plate DBD). The experimental results show that the application of airflow to the DBD can reinforce discharge and improve the discharge uniformity. When airflow increases to a certain velocity, surface discharge can transform into diffuse volume discharge. Moreover, the application of a magnetic field to DBD in static air can also enhance discharge, which is manifested as the enhancement of surface discharge. A similar but more significant effect is obtained in DBD combined airflow with magnetic field. Compared with the DBD with airflow only, the transition from surface discharge to diffuse volume discharge in DBD combined airflow with magnetic field occurs at a smaller airflow velocity. Besides, DBD combined airflow with magnetic field under different pulse repetition frequencies (PRFs) is also investigated. The results show that the minimum velocity required to generate diffuse volume discharge also shrinks with the decrease in PRF. In short, it is easier to generate diffuse volume discharge under the conditions of airflow, magnetic field, and lower PRF. The underlying physical mechanism of the above phenomena is discussed and mainly ascribed to the enhanced ionization by applying airflow, magnetic field, and lower PRF.