Magnetic particle hyperthermia—biophysical limitations of a visionary tumour therapy

Loss processes being relevant for magnetic particle hyperthermia are analysed with respect to specific loss power under the condition of a limitation of the alternating magnetic field amplitude and frequency. Extrapolations to the maximum specific loss power of magnetic nanoparticles are discussed and conclusions are drawn with respect to the minimum particle concentration being necessary for hyperthermia or thermoablation under intra-tumoural or systemic particle supply. As a result, much efforts are necessary to render magnetic particle hyperthermia a valuable tumour therapy keeping at least part of the promises found in literature.     

空间高频交变磁场对超导块材悬浮力影响研究

高温超导磁悬浮装置,如磁悬浮列车和磁悬浮轴承在高速运行时,空间磁场交变及不均匀性扰动会引发超导块材内部损耗并影响性能,传统均匀时变磁场实验研究及仿真模拟无法满足实际工程应用情况.本文通过设计不同永磁阵列得到不同波形,在高速系统驱动下得到不同交变频率下超导块材损耗特性,发现全波型损耗较半波型损耗高,并研究了不同磁场构型悬浮力衰减特性,可为高速超导磁浮应用提供实验依据.     

Peak Profile Analysis in High Field Asymmetric Wave Ion Mobility Spectrometry

High field asymmetric wave ion mobility spectrometry (FAIMS) is a powerful tool to detect and characterize gas-phase ions, while the unsolvable partial differential equation of ions moving in ion drift tube poses a big challenge to FAIMS spectral peak analysis. In this work, a universal and effective model of FAIMS spectral peak profile has been proposed by introducing ion trajectory and loss height. With this model, the influence of the structure of ion drift tube, dispersion voltages, compensation voltages, and carrier gas flow rate on the FAIMS spectral peak characteristics like peak shape, full width at half maximum and peak height is analyzed and discussed. The results show that the influence of different factors on the FAIMS spectral peak profile can be qualitatively described by the model which agrees with the experimental data.     

Measurement of Dynamic Properties of Viscoelastic Materials

An improved method to measure the dynamic viscoelastic properties of elastomers is proposed. The method is based on the analysis of forced oscillation of a cylindrical sample loaded with an inertial mass. No special equipment or instrumentation other than the ordinary vibration measurement apparatus is required. Upper and lower surfaces of the viscoelastic material sample were bonded to a load disc and a rigid base plate, respectively. The rigid base plate was subject to forced oscillations driven by a vibration exciter. Two accelerometers were attached to monitor the displacement of the base plate and the load disc. The recorded magnitude ratio and the phase difference between the load disc and the base plate vibrations represent the axial, dynamic deformation of the sample. The data are sufficient to obtain the dynamic properties of the sample, oscillation properties of vibration exciter, whereas the sensitivity of gauges having no effect on the calculation results. For accurate calculation of the properties, a two-dimensional numerical model of cylindrical sample deformation was used. Therefore, a form factor, which takes into account the sample sizes in one-dimensional models, is not required in this method. Typical measurement of the viscoelastic properties of a silicone rubber Silastic® S2 were measured over the frequency range from 10 Hz to 3 kHz under deformations (ratio of vibration magnitude to sample thickness) from 10^?4% to 5%. It was shown that the modulus of elasticity and the loss tangent fall on a single curve when the ratio of load mass to sample mass changed from 1 to 20. When the sample diameter was varied from 8 to 40 mm, the modulus of elasticity fall on the same curve, but the loss tangent curves showed some degree of scatter. Studied temperature dependence and nonlinear behavior of viscoelastic properties is found not to be associated with this effect.     

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%。     

Steady state of loss systems with a superposition of inputs

The total input of a loss system consisting of a finite number of fully available, identical servers is assumed to be a superposition of a finite number of partial traffic streams, which need not be independent and which are represented by a random marked point process. This paper derives existence, uniqueness and ergodic statements for the steady state of the system at several observation points, i.e. at an arbitrary point in time and at the arrival instants of calls belonging to a fixed partial stream.     

新洲县东部低山丘陵水土流失的研究

本文分析了新洲县东部低山丘陵区水土流失成因,阐述了该区土壤侵蚀形式、程度和分布的特点,并应用实地观测资料推导了土壤流失预测方程和进行了主成分分析研究,从而为该区水土流失治理措施提供科学依据,这在鄂东大别山南麓地区具有一定代表性.     

Oscillating minimizers of a fourth-order problem invariant under scaling

By variational methods, we prove the inequality

     

Wald意义下的局部π—Bayes最优决策

本文在某些必要的条件下，证明ｗａｌｄ意义下的最优决策的存在性。并表明：ｗａｌｄ意义下的最优决策作为一种π－Ｒａｙｅｓ最优决策实际上是局部的。     

Approximating the departure process from aG/G/1 loss system

The departure process from aG/G/1 loss system with generally distributed interarrival time, generally distributed service time, a single server, and no waiting room is approximated in steady state. Furthermore, the tandem behavior of the system is approximated, approximation results are provided, and are compared against those from a simulation study.

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Zusammenfassung Für das BedienungsmodellG/G/1 ohne Warteraum wird eine Approximation des Abgangsprozesses im stationären Zustand angegeben, wobei allgemein verteilte Zwischenankunfts- und Bedienungszeiten angenommen sind. Ferner werden für den Fall, daß mehrere solche Bediener in Reihen geschaltet sind, approximative Resultate angegeben und mit Simulationen überprüft.