A thermo-fluid analysis in magnetic hyperthermia

In the last years, hyperthermia induced by the heating of magnetic nanoparticles （MNPs） in an alternating magnetic field received considerable attention in cancer therapy. The thermal effects could be automatically controlled by using MNPs with selective magnetic absorption properties. In this paper, we analyze the temperature field determined by the heating of MNPs, injected in a malignant tissue, subjected to an alternating magnetic field. The main parameters which have a strong influence on temperature field are analyzed. The temperature evolution within healthy and tumor tissues are analyzed by finite element method （FEM） simulations in a thermo-fluid model. The cooling effect produced by blood flow in blood vessels from the tumor is considered. A thermal analysis is conducted under different distributions of MNP injection sites. The interdependence between the optimum dose of the nanoparticles and various types of tumors is investigated in order to understand their thermal effect on hyperthermia therapy. The control of the temperature field in the tumor and healthy tissues is an important step in the healing treatment.     

一种基于多普勒频移的被动合成孔径声纳探测方法*

由于自主小平台声纳孔径有限,对声纳探测的分辨率的提高有所限制。小平台的机动可以有效的与声纳探测方法相结合来提高声纳探测性能。针对这一特点,提出一种基于多普勒频移技术的被动合成孔径声纳探测方法。该方法根据自主小平台的机动所引起声纳的接收信号多普勒频移的变化,进行目标的频率与方位联合估计。本文将自主小平台的机动引入到波束形成技术当中形成一种新的被动合成孔径技术。数值仿真表明,该方法可以有效的进行目标方位估计,并且获得较高的方位分辨率,改善了自主小平台的探测性能。     

用模糊算子法对用通俗语言描述的颜色标志的定量评价

本文在确定颜色模糊性的基础上,用模糊算子的方法分析了用通俗语言描述的颜色标志,提出了一种颜色标志的定量方法。     

Quantitative properties of colour singlet clusters in QCD jets

Using a Monte Carlo technique we have made detailed calculations of the properties of colour singlet clusters in QCD jets, first discussed by Amati and Veneziano. Although the results confirm a mass damping for colour singlets, we find that, quantitatively, it is not enough to justify a phenomenological use of colour singlets as an intermediate step in the materialization of QCD quanta into hadrons.     

Quantitative measurements of injections into porous media with contrast based MRI

Porous flow occurs in a wide range of materials and applies to many commercially relevant applications such as oil recovery, chemical reactors and contaminant transport in soils. Typically, breakthrough and pressure curves of column floods are used in the laboratory characterization of these materials. These characterization methods lack the detail to easily and unambiguously resolve flow mechanisms with similar effects at the core scale that can dominate at the aquifer or oil field scale, as well as the effects of geometry that control the flow at interfaces as in a perforated well or the inlet of an improperly designed column. Non-invasive imaging techniques such as MRI have been shown to provide a far more detailed characterization of the properties of the solid matrix and flow, but usually focus on the intrinsic flow properties of porous media or matching a numerical model to a complex flow system. We show that these MRI techniques, utilizing paramagnetic tagging in combination with a carefully controlled and ideal flow system, can quantitatively characterize the effects of geometry and intrinsic flow properties for a point injection into a core. The use of a carefully controlled and 'idealized' system is essential to be able to isolate and match predicted effects from geometry and extract subtle flow processes omitted in the model that would be hidden in a more heterogeneous system. This approach provides not only a tool to understand the behavior of intentional boundary effects, but also one to diagnose the unintentional ones that often degrade the data from routine column flood measurements.     

Quantitative shearography in axisymmetric gas temperature measurements

This paper describes the use of shearing interferometry (shearography) for the quantitative measurement of gas temperatures in axisymmetric systems in which vibration and shock are substantial, and measurement time is limited. The setup and principle of operation of the interferometer are described, as well as Fourier-transform-based fringe pattern analysis, Abel transform, and sensitivity of the phase lead to temperature calculation. A helium jet and a Bunsen burner flame are shown as verification of the diagnostic. The accuracy of the measured temperature profile is shown to be limited by the Abel transform and is critically dependent on the reference temperature used.     

Semiclassical dynamics from Zeno-like measurements

The usual semiclassical approximation for atom-field dynamics consists in substituting the field operators by complex numbers related to the (supposedly large enough) intensity of the field. We show that a semiclassical evolution for coupled systems can always be obtained by frequent Zeno-like measurements on the state of one subsystems, independently of the field intensity in the example given. We study the Jaynes-Cummings model from this perspective.     

Variable-rate colour image quantization based on quadtree segmentation

A novel variable-sized block encoding with threshold control for colour image quantization (CIQ) is presented in this paper. In CIQ, the colour palette used has a great influence on the reconstructed image quality. Typically, a higher image quality and a larger storage cost are obtained when a larger-sized palette is used in CIQ. To cut down the storage cost while preserving quality of the reconstructed images, the threshold control policy for quadtree segmentation is used in this paper. Experimental results show that the proposed method adaptively provides desired bit rates while having better image qualities comparing to CIQ with the usage of multiple palettes of different sizes.     

Quantitative nondestructive measurements of residual stresses

A stress maintained in the bulk of a material without application of an external traction (excluding gravity) or other sources, such as a thermal gradient, is called a residual stress. All residual stress systems have zero resultant force, the body being in equilibrium. The distance or range over which the stresses achieve this balance may be grouped into three classes as presented in Table 1. Also shown are the effects that the given examples exhibit using x-ray diffraction, the most popular technique to investigate residual stresses.     

Lifetime measurements of colour centres by a multifrequency phase fluorometer

Summary The first measurements of emission lifetimes in colour centres using a cross correlation phase and modulation fluorometer operating at the synchrotron radiation facility PULS (Frascati) are reported. Preliminary results on the F and F-aggregate centres in NaF are briefly summarized.

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Riassunto Si riportano le prime misure di tempi di vita dell'emissione dei centri di colore usando uno spettrofluorometro a correlazione di fase e di modulazione in funzione presso il laboratorio del Programma per l'Utilizzazione della Luce di Sincrotrone (PULS, Frascati). Si discutono i risultati relativi ai centri F ed agli aggregati di centri F nel fluoruro di sodio.

     

Optimal data processing for quantum measurements

We consider the general measurement scenario in which the ensemble average of an operator is determined via suitable data processing of the outcomes of a quantum measurement described by a positive operator-valued measure. We determine the optimal processing that minimizes the statistical error of the estimation.     

Computer-aided processing of optical measurements in aeroballistic experiment

The idea of semiautomatic computer-aided processing of photos as applied to the problem of external ballistics, namely, determination of aerodynamic characteristics of flying objects from trajectory data, is put forward. The impetus to write this article is the development of an original software product that was used to advantage in processing data of full-scale experiments with the aim of creating a photo database of ballistic experiments performed at the Ioffe Physicotechnical Institute. This software is integrated into the Arkhimed information-retrieval system used to control this database. The advantages of the semiautomatic approach over “manual” measurements and the fully automatic version are indicated.     

Thwarted dynamics by partial projective measurements

The dynamics of a system made of a particle interacting with a field mode “thwarted” by the action of repeated projective measurements on the particle is examined. The effect of the partial measurements is discussed by comparing it with the dynamics in the absence of the measurements.     

Microscopic information processing and communication in crowd dynamics

Due, perhaps, to the historical division of crowd dynamics research into psychological and engineering approaches, microscopic crowd models have tended toward modelling simple interchangeable particles with an emphasis on the simulation of physical factors. Despite the fact that people have complex (non-panic) behaviours in crowd disasters, important human factors in crowd dynamics such as information discovery and processing, changing goals and communication have not yet been well integrated at the microscopic level. We use our Microscopic Human Factors methodology to fuse a microscopic simulation of these human factors with a popular microscopic crowd model. By tightly integrating human factors with the existing model we can study the effects on the physical domain (movement, force and crowd safety) when human behaviour (information processing and communication) is introduced.In a large-room egress scenario with ample exits, information discovery and processing yields a crowd of non-interchangeable individuals who, despite close proximity, have different goals due to their different beliefs. This crowd heterogeneity leads to complex inter-particle interactions such as jamming transitions in open space; at high crowd energies, we found a freezing by heating effect (reminiscent of the disaster at Central Lenin Stadium in 1982) in which a barrier formation of naïve individuals trying to reach blocked exits prevented knowledgeable ones from exiting. Communication, when introduced, reduced this barrier formation, increasing both exit rates and crowd safety.     

Adaptive beamforming for array signal processing in aeroacoustic measurements

Phased microphone arrays have become an important tool in the localization of noise sources for aeroacoustic applications. In most practical aerospace cases the conventional beamforming algorithm of the delay-and-sum type has been adopted. Conventional beamforming cannot take advantage of knowledge of the noise field, and thus has poorer resolution in the presence of noise and interference. Adaptive beamforming has been used for more than three decades to address these issues and has already achieved various degrees of success in areas of communication and sonar. In this work an adaptive beamforming algorithm designed specifically for aeroacoustic applications is discussed and applied to practical experimental data. It shows that the adaptive beamforming method could save significant amounts of post-processing time for a deconvolution method. For example, the adaptive beamforming method is able to reduce the DAMAS computation time by at least 60% for the practical case considered in this work. Therefore, adaptive beamforming can be considered as a promising signal processing method for aeroacoustic measurements.     

Protein dynamics measurements by TROSY-based NMR experiments

The described TROSY-based experiments for investigating backbone dynamics of proteins make it possible to elucidate internal motions in large proteins via measurements of T(1), T(2), and NOE of backbone (15)N nuclei. In our proposed sequences, the INEPT sequence is eliminated and the PEP sequence is replaced by the ST2-PT sequence from the HSQC-based experiments. This has the benefit of shortening the pulse sequences by 5.4 ms (=1/2J) and results in an increase in the intrinsic sensitivity of the proposed TROSY-based experiments. The TROSY-based experiments are on average of 13% more sensitive than the corresponding HSQC-based experiments on a uniformly (15)N-labeled Xenopus laevis calcium-bound calmodulin sample on a 750-MHz spectrometer at 5 degrees C. The amide proton linewidths of the TROSY-based experiments are 2-13 Hz narrower than those of the HSQC experiments. More sensitivity gain and higher resolution are expected if the protein sample is deuterated.     

Monoenergetic-proton-radiography measurements of implosion dynamics in direct-drive inertial-confinement fusion

Time-gated, monoenergetic radiography with 15-MeV protons provides unique measurements of implosion dynamics in direct-drive inertial-confinement fusion. Images obtained during acceleration, coasting, deceleration, and stagnation display a comprehensive picture of spherical implosions. Critical information inferred from such images, hitherto unavailable, characterizes the spatial structure and temporal evolution of self-generated fields and plasma areal density. Results include the first observation of a radial electric field inside the imploding capsule. It is initially directed inward (at approximately 10(9) V/m), eventually reverses direction ( approximately 10(8) V/m), and is the probable consequence of the evolution of the electron pressure gradient.     

Optical measurements of plasma dynamics in carbon fiber Z-pinches

A series of experiments has been carried out on the Mega Ampere Generator for Plasma Implosion Experiments (MAGPIE) generator in order to study the dynamics of carbon fiber Z-pinches. The generator was operated at 1.4 MV, with a peak current of 1 MA, and a rise time of 150 ns. In some shots, a current prepulse of about 30 kA was provided to study its influence on the dynamics of the fiber pinch. Carbon fibers of 7, 33, and 300 μm diameter were used during these experiments. The diagnostics employed were a self-referencing interferometer, a two-frame Schlieren system, an optical streak camera, and a four-frame X-ray framing camera. A novel feature of these measurements is the employment of an optical streak camera with a set of four slits arranged along the fiber axis and displaced in the radial direction. This permitted the study of the temporal evolution (axial and radial) of the plasma regions emitting in the visible part of the spectra. Correlation between these regions of the plasma and the location of X-ray hot spots is discussed. In carbon fibers of 33 pm diameter, the radial expansion velocity measured from Schlieren images was 3.6×10⁶ cm/s and 5.5×10⁶ cm/s for shots with and without prepulse, respectively. The dominant axial wavelengths of instabilities in the coronal plasma were between 0.05 and 0.2 cm, which correspond to ka values between 10 and 20, where k is the wavenumber of the instability and a is its amplitude. The dynamics of carbon fibers of different diameters are compared     

Quantitative temperature field measurements on a non-gray multi-materials scene by thermoreflectometry

This article addresses the problem of measuring an accurate temperature field on a multi-materials scene composed of two dielectric and one metallic materials. The measurements of thermo-radiative properties demonstrate that the scene exhibit very different emissivity spectra and thermal conductivities inducing high thermal gradients. From these radiative properties, the calculation of the theoretical temperature error of conventional passive methods highlights that a method may be suitable for measuring only one material but no method provides satisfactory measurements of the sets of materials. The proposed method, called thermoreflectometry, performs a simultaneous measurement on all materials thanks to an on-line indirect determination of emissivity based on a bidirectional reflectivity measurement. Its temperature error is compared to that of the selected passive method for each material through an experimental validation on the multi-materials scene. These results highlight the accuracy of thermoreflectometry and shows opening prospects for the on-line temperature control of dynamical processes.