线、面模型的电荷“体分布”函数

线电荷及面电荷是两个重要的物理模型 .针对求解有关物理问题的特殊需要 ,将线模型及面模型的电荷分布之线密度和面密度表征为“体分布” ;δ函数是一种分布 ,在物理上是理想的点模型 .利用点模型 ,表征了三种理想的线模型及面模型的电荷“体分布” ρ (r1)

Doxorubicin Stealth Liposomes Prepared with PEG-Distearoyl Phosphatidylethanolamine and Distribution as well as Antitumor Activity in Mice

目的：研制出能够逃避体内网状内皮细胞的阿霉素隐形脂质体，并考察其在生物体内的分布以及比较阿霉素隐形脂质体与阿霉素普通脂质体的抗肿瘤活性。方法：将聚乙二醇－二硬脂酰磷脂酰乙醇胺（PEG－DSPE）同磷脂酰胆碱和胆固醇材料加在一起，用硫酸铵梯度法制备阿霉素隐形脂质体，同法制备阿霉素普通脂质体（但脂膜中不含PEG－DSPE）；通过尾静脉注射给药，比较隐形脂质体阿霉素、普通脂质体阿霉素和游离型阿霉素（盐酸阿霉素注射液）给药后在小鼠各主要脏器组织和血液中的分布情况；采用动物移植性肿瘤实验法，用H22小鼠肝癌细胞接种于小鼠右侧腋皮下形成实体瘤，考察阿霉素隐形脂质体和普通脂质体给药后对实体瘤的瘤重抑制率。结果：通过硫酸铵梯度法制备出了包封率高达95％的阿霉素隐形脂质体；同游离型阿霉素和普通脂质体阿霉素相比，隐形脂质体阿霉素在血液中浓度显著提高，循环时间显著延长，在心脏中分布的浓度显著降低；按5mg·kg^-1剂量治疗，第二天给药和第七天给药治疗方案，阿霉素隐形脂质体给药组的瘤重抑制率均显著高于普通脂质体给药组的瘤重抑制率；按10mg·kg^-1剂量治疗，隐形脂质体给药组的瘤重抑制率比普通脂质体给药组的瘤重抑制率稍高。结论：用普通脂质体给药相比，隐形脂质体阿霉素给药后延长了其在小鼠血液中的循环时间，说明经过PEG－DSPE修饰后的脂质体有逃避网状内皮细胞吞噬的功能（隐形），并且隐形脂质体阿霉素的抗肿瘤活性显著地提高。

Distribution and Length-weight Relationships of Glyptosternoid Fishes in the Drung River Basin, Yunnan

Glyptosternoid fishes are a group of sisorid catfishes living in torrents of rivers mainly originating from the Qinghai-Tibet Plateau. Based on our survey in the Drung River Basin, seven collecting sites were investigated and 271 glyptosternoid fishes caught belong to three species （Pareuchiloglanis kamengensis, Exostoma labiatum and Oreoglanis mocropterus）. Features of the distribution of the three catfishes were assessed. More individuals of E. labiatum were caught in the lower reaches of the Drung River with fast water velocity and it might be more adapted to a torrent habitat. The relationships between standard length （L） and weight （W） for P. kamengensis, E. labiatum and O. macropterus were also studied, and the parameter b of the L-W relationship （W = aL^b） ranged between 2. 8201 and 3. 0131. From the present study, all the three catfish species grow allometrically and the growth type of E. labiatum is the closest to a symmetrical one.

Numerical simulation of flow regions in red mud separation thickener's feedwell by analysis of residence-time distribution

The residence-time distribution （RTD） and the compartment model were applied to characterizing the flow regions in red mud separation thickener’s feedwells. Combined with the experimental work, validated mathematical model as well as three-dimensional computational fluid dynamics （CFD） model was established to analyze the flow regions of feedwells on an industrial scale. The concept of RTD, although a well-known method for the characterization of mixing behavior in conventional mixers and reactors, is still a novel measure for the characterization of mixing in feedwells. Numerical simulation results show that the inlet feed rate and the aspect ratio of feedwells are the most critical parameters which affect the RTD of feedwell. Further simulation experiments were then carried out. Under the optimal operation conditions, the volume fraction of dead zone can reduce by10.8% and an increasement of mixing flow volume fraction by 6.5% is also observed. There is an optimum feed inlet rate depending on the feedwell design. The CFD model in conjunction with the RTD analysis then can be used as an effective tool in the design, evaluation and optimization of thickener feedwell in the red mud separation.

Comparative Efficacy and Distribution of Evans Blue Liposome Modified with DSPE-PEG,Tween80,and Brij35

Aim To improve the stability and optimize the tissue distribution of Evans blue liposome in rats, some surfactants such as DSPE-PEG, Tween80, and Brij35 were used to modify the Evans blue liposome. Methods The Evans blue liposome was prepared by the reverse-phase-evaporation method. The effect of cholesterol on the encapsulation percentage of Evans blue was studied. The effects of DSPE-PEG, Tween80, and Brij35 on the encapsulation percentage and tissue distribution of Evans blue liposome in the rat were determined. Results The top encapsulation percentage of Evans blue liposome is 25.30%. After modification by DSPE-PEG, Tween80, and Brij35, the encapsulation percentages decreased slightly, but not significantly. After modification, the Evans blue concentrations deceased in the liver, spleen, lung and kidney, but increased in the brain, especially in the EB-L-Tween80 group. Conclusion DSPE-PEG, Tween80, and Brij35 have slight effect on the encapsulation percentage of Evans blue liposome. The effect of Brij35 on the distribution of Evans blue liposome is similar to that of DSPE-PEG because they both is prevent the reticuloendothelial system (RES) from clearing liposome. The Evans blue concentration in the brain is greatly improved when Tween80 is used to modify the EB liposome, which is good information for preparing liposome targeting the brain.

Optimum design of flow distribution in quenching tank for heat treatment of A357 aluminum alloy large complicated thin-wall workpieces by CFD simulation and ANN approach

Based on the computational fluid dynamics （CFD） method, a quenching tank with two agitator systems and two flow-equilibrating devices was selected to simulate flow distribution using Fluent software. A numerical example was used to testify the validity of the quenching tank model. In order to take tank parameters （agitation speed, position of directional flow baffle and coordinate position in quench zone） into account, an approach that combines the artificial neural network （ANN） with CFD method was developed to study the flow distribution in the quenching tank. The flow rate of the quenching medium shows a very good agreement between the ANN predicted results and the Fluent simulated data. Methods for the optimal design of the quenching tank can be used as technical support for industrial production.

CFD-supported optimization of flow distribution in quench tank for heat treatment of A357 alloy large complicated components

The flow distribution in quench tank for heat treatment of A357 alloy large complicated components was simulated using FLUENT computational fluid dynamics（CFD） software.The flow velocity and the uniformity of flow field in two types of quench tanks（with or without agitation system） were calculated.The results show that the flow field in the quench tank without agitation system has not evident regularity.While as for the quench tank with agitation system,the flow fields in different parameters have certain regularity.The agitation tanks have a distinct advantage over the system without agitation.Proper process parameters were also obtained.Finally,the tank model established in this work was testified by an example from publication.This model with high accuracy is able to optimize the tank structures and can be helpful for industrial production and theoretical investigation in the fields of heat treatment of large complicated components.

Parallel Implementation of Global Illumination Using PVM

In this paper an attempt of employing network resources to solve a complex and time-consuming problem is presented. The global illumination problem is selected as the study objective. An improved density estimation algorithm is first developed, in which the more inherent concurrency is explored. Then its parallel implementation by using a PVM mechanism and the running performance analysis are provided. The analysis results show the expected speed-up obtained and demonstrate that the PVM has good application prospects for parallel computation in a distributed network.

Products of carbothermic reduction of Fe-Cr-O and Fe-Cr-Ni-O systems

The reduction behaviors and characteristics of products of the Fe-Cr-O system （FeCr2O4 and Fe2O3＋Cr2O3） and Fe-Cr-Ni-O system （Fe2O3＋Cr2O3＋NiO） under various conditions were studied. The results show that more Fe-Cr or Fe-Cr-Ni solution and less residual carbon content were obtained at higher temperatures and lower initial molar ratio of C to O （nC：nO）. The degree of reduction was highly dependent on both time and temperature, and the residual carbon content greatly increased with increasing nC：nO at each temperature. The products generated during the carbothermic reduction of the Fe-Cr-O system were examined using X-ray diffraction （XRD）. A scanning electron microscope （SEM） coupled with energy dispersive spectrometer was used to observe the microstructure and the distribution of elements in the various phases of the final reduction products of the Fe-Cr-O and Fe-Cr-Ni-O.

Performance enhancement of IEEE 802.11 distributed coordination function for MANET

The medium access control (MAC) issue was discussed in mobile Ad Hoc networks (MANETs). Based on the IEEE 802.11 MAC protocol, this paper proposed two schemes, the forward-packet-first (FPF) scheme based on the adaptive backoff contention window and multihop forward chain transmission by invitation (MFCTI) scheme. In the FPF scheme, the contention window was adjusted adaptively according to the traffic priority. Route information and the broadcast characteristic of radio were utilized in MFCTI scheme. The performance of these schemes was studied in multihop environments by simulations. The results showed that the proposed schemes could improve the network throughput, reduce the end-to-end average delay, and mitigate local congestion effectively. Another attractive feature was that the schemes could be implemented with minor modifications to the IEEE 802.11 MAC.

A New Quasi 2-Dimensional Analytical Approach to Predicting Ring Junction Voltage,Edge Peak Fields and Optimal Spacing of Planar Junction with Single Floating Field Limiting Ring Structure

WT8.BZ]A new quasi 2-dimensional analytical approach to predicting the ring voltage,edge peak fields and optimal spacing of the planar junction with a single floating field limiting ring structure has been proposed,based on the cylindrical symmetric solution and the critical field concept.The effects of the spacing and reverse voltage on the ring junction voltage and edge peak field profiles have been analyzed.The optimal spacing and the maximum breakdown voltage of the structure have also been obtained.The analytical results are in excellent agreement with that obtained from the 2-D device simulator,MEDICI and the reported result,which proves the presented model valid.

A STUDY OF DETERMINING MICROPORE VOLUME OF ACTIVATED CARBON BY MERCURY POROSIMETRY

The Micro pore volume in porous materials usually interests many researchers. However, there has been few, if not, direct method to determine it. A strategy of combining mercury porosimetry with pre adsorption is proposed in the present paper. The total pore volume in activated carbon is determined through direct measurements for the first time. The application scope of mercury porosimetry is also enlarged. Besides, the present experiments also confirmed the preference of adsorption to the smaller pores even in the range of meso and macro pores.

STABILITY ANALYSIS AND COOPERATIVE CONTROL OF DISTRIBUTED MULTI-AGENT SYSTEM WITH SAMPLED COMMUNICATION

The cooperative control and stability analysis problems for the multi-agent system with sampled com- munication are investigated. Distributed state feedback controllers are adopted for the cooperation of networked agents. A theorem in the form of linear matrix inequalities（LMI） is derived to analyze the system stability. An- other theorem in the form of optimization problem subject to LMI constraints is proposed to design the controller, and then the algorithm is presented. The simulation results verify the validity and the effectiveness of the pro- posed approach.

CFD Simulation and Experimental Validation of Fluid Flow in Pre-distributor

Liquid distributor is a very import intemal for distillation columns. Pre-distributor is usually set on the top of distributor for initial distribution. Fluid flow in pre-distributor is a complex system of variable mass flow with many orifices and sub-branches. Consequently, the two phase modeling of pre-distributors was carried out andthe homogeneous model with free surface model was applied. The numerical method was validated by comparing with experimental data. Using the simulated results for different pre-distributors, the impacts of inflow rate, location and orientation uoon the outflow distribution were investigated. Furthermore, influences of the outflow distribution for pre-distributor on liquid uniformity in trough were also analyzed, The conclusions can De aaoptea for me structural design of liquid distributor and pre-distributor of large scale.

The Relationship Between Hysteresis and Liquid Flow Distribution in Trickle Beds

Experiments were conducted on a trickle bed with 0.283m ID to elucidate the relationship between hysteretic phenomena and liquid distribution. The hysteresis of pressure drop and the variance of radial liquid distribution were observed simultaneously. Residence time distribution (RTD), holdup and mean residence time (RT) of liquid phase were also found to demonstrate hysteresis of the same nature. RTD, liquid holdup and mean RT calculated with a simple model from the distribution of liquid flow rate show characteristics consistant with the experimental data, suggesting that the hyteretic phenomena originate from the multiplicity and nonuniformity of liquid flow distribution.

Paleogeomorphy,provenance system and sedimentary system of the Dongying formation in the Qikou sag

Reconstructed synsedimentary paleogeomorpholgy is an effective method in predicting the distribution of sandbodies and can provide valid evidence in the search for reservoirs. Based on a synsedimentary paleogeomorpholgy reconstruction of the third member of the Dongying formation (Ed3) in the Qikou sag,the basic paleogeomorphic characteristics of Ed3 are described and the spatial distributions of denudation and subsidence areas are discussed. Key boundary faults controlling the deposition of important sediment bodies are proposed and the interrelations among faulted slope-break belts or flexure belts,intra-depression uplifts and sags,sediment sources and sediments input points have been investigated.

Connection Between Liquid Distribution and Gas-Liquid Mass Transfer in Monolithic Bed

With a particular focus on the connection between liquid flow distribution and gas-liquid mass transfer in monolithic beds in the Taylor flow regime, hydrodynamic and gas-liquid mass transfer experiments were carriedout in a column with a monolithic bed of cell density of 50 cpsi with trio different distributors （nozzle and packed bed distributors）. Liquid saturation in individual channels was measured by using self-made micro-conductivity probes. A mal-distribution factor was used to evaluate uniform degree of phase distribution in monoliths. Overall bed pressure drop and mass transfer coefficients were measured. For liquid flow distribution and gas-liquid masstransfer, it is found that the superficial liquid velocity is a crucial factor and the packed bed distributor is better than the nozzle distributor. A semi-theoretical analysis using single channel models shows that the packed bed distributor always yields shorter and uniformly distributed liquid slugs compared to the nozzle distributor, which in turn ensures a better mass transfer performance. A bed scale mass transfer model is proposed by employing the single channel models in individual channels and incorporating effects of non-uniform liquid distribution along the bedcross-section. The model predicts the overall gas-liquid mass transfer coefficient wig a relative error within ＋30%.

Understanding pollution dynamics in large-scale peer-to-peer IPTV system

With the great commercial success of several IPTV (internet protocal television) applications, PPLive has received more and more attention from both industry and academia. At present, PPLive system is one of the most popular instances of IPTV applications which attract a large number of users across the globe; however, the dramatic rise in popularity makes it more likely to become a vulnerable target. The main contribution of this work is twofold. Firstly, a dedicated distributed crawler system was proposed and its crawling performance was analyzed, which was used to evaluate the impact of pollution attack in P2P live streaming system. The measurement results reveal that the crawler system with distributed architecture could capture PPLive overlay snapshots with more efficient way than previous crawlers. To the best of our knowledge, our study work is the first to employ distributed architecture idea to design crawler system and discuss the crawling performance of capturing accurate overlay snapshots for P2P live streaming system. Secondly, a feasible and effective pollution architecture was proposed to deploy content pollution attack in a real-world P2P live streaming system called PPLive, and deeply evaluate the impact of pollution attack from following five aspects:dynamic evolution of participating users, user lifetime characteristics, user connectivity-performance, dynamic evolution of uploading polluted chunks and dynamic evolution of pollution ratio. Specifically, the experiment results show that a single polluter is capable of compromising all the system and its destructiveness is severe.

CFD Analysis of Gas Distributor in Packed Column ——Prediction of Gas Flow and Effect of Tower Internals Geometry Structure

Computational fluid dynamics (CFD) simulations were carried out on the gas flow patterns of twin-tangential annular deflector gas distributor in the absence of liquid flow in a packed column (6.4 m in diameter), and the gas flow field in the column was presented close to reality on the whole. Furthermore, after ame-(lioration) of this gas distributor frame, turbulence energy and turbulence energy dissipation rate were both decreased greatly.Simulation results showed that the flow pattern and the distribution of gas flow were strongly affected by the column bottom frame; the proper column bottom frame could decrease the flow pressure drop greatly. Multifold factors, such as the column bottom geometry structure and distributor structure which affects the distribution capacity, must be considered.

Comparison of Gas Distribution Properties of Conventional and High Capacity Structured Packings

This paper presents the results of an experimental study carried out using large scale equipment to observe the effect of geometry on gas distribution properties of a high capacity corrugated sheet structured packing （Montz-pak B 1-250M） and to compare it with that of its conventional counterpart （Montz-pak B1-250）. Although the high capacity packing exhibits a significantly lower overall pressure drop, the gas distribution performance is similar to that of the conventional packing, and in both cases consistently good one.