Modeling and simulation of drug delivery from a new type of biodegradable polymer micro-device

In this paper, modeling and simulation of a new type of controlled drug delivery micro-device based on biodegradable polymers is reported. The micro-device consists of micro-chambers arrays for drug storage to achieve linear release. The micro-chambers are fabricated with polyanhydrides (CPP-SA) using the UV-LIGA technology and the controlled release process are the combined results of the design of the micro-chambers and the biodegradable characteristics of the polymer. This type of drug delivery system has some unique advantages in controlled long-term drug delivery, such as larger loading volume than the matrices release systems, easier control for the release rate, etc. It is necessary to optimize the structure for the long-term and zero-order drug release. Based on the Monte Carlo erosion model, the drug release model is founded for the drug delivery system and using the new model, the drug release profiles from the delivery systems with different structures are simulated. The simulated results indicate that the effect of the drug delivery is dependent on the micro-structure of the delivery system and the simulated drug profiles of coaxial rings micro-cavity shape equal to zero-order released model approximatively. The simulated results are very important to the application research of the new biodegradable polymer micro-device.     

Natural convection heat transfer of water on a horizontal downward facing stainless steel disk in a gap under atmospheric pressure conditions

An experimental study on natural convection heat transfer on a horizontal downward facing heated surface in a water gap has been carried out under atmospheric pressure conditions. A total of 7204 experimental data points are correlated using Rayleigh versus Nusselt number correlations in various forms, based on different independent variables. The effects of different characteristic lengths and film temperatures are discussed. The buoyancy force acts as a resistance force for natural convection heat transfer on a downward facing horizontal heated surface in a confined space. For the estimation of the natural convection heat transfer under the present conditions, empirical correlations in which Nusselt number is expressed as a function of Rayleigh number, or Rayleigh and Prandtl numbers both, may be used. However, the best accuracy is provided by an empirical correlation which expresses the Nusselt number as a function of the Rayleigh and Prandtl numbers, as well as the gap width-to-heated surface diameter ratio; and uses the temperature difference between the heated surface and the ambient fluid in the definition of Rayleigh number. The characteristic length is the gap size and the film temperature is the average fluid temperature.     

Poisson image fusion based on Markov random field fusion model

In this paper, we present a gradient domain image fusion framework based on the Markov Random Field (MRF) fusion model. In this framework, the salient structures of the input images are fused in the gradient domain, then the final fused image is reconstructed by solving a Poisson equation which forces the gradients of the fused image to be close to the fused gradients. To fuse the structures in the gradient domain, an effective MRF-based fusion model is designed based on both the per-pixel fusion rule defined by the local saliency and also the smoothness constraints over the fusion weights, which is optimized by graph cut algorithm. This MRF-based fusion model enables the accurate estimation of region-based fusion weights for the salient objects or structures. We apply this method to the applications of multi-sensor image fusion, including infrared and visible image fusion, multi-focus image fusion and medical image fusion. Extensive experiments and comparisons show that the proposed fusion model is able to better fuse the multi-sensor images and produces high-quality fusion results compared with the other state-of-the-art methods.     

资源受限网络中高效XML交换的性能评估

为了研究高效XML交换(EXI)在资源受限网络中的使用情况,文中基于传感器观测服务的真实数据,对四种交换模式下的数据大小进行了对比:XML、高效XML、Gzip压缩的XML以及开启压缩模式的高效XML。通过在ns-2中建模,对资源受限网络环境下各交换格式的平均成功率、平均延时、平均能量消耗等性能进行了分析。实验结果表明,无论是否开启压缩模式,高效XML比XML具有更小的体积、更高的成功率、更短的延时和更少的能量消耗。高效XML交换更加适合于资源受限网络。     

Decision tree classifiers sensitive to heterogeneous costs

There are nine major types of cost involved in cost-sensitive learning that are with heterogeneous units in general, referred to heterogeneous costs. Extant cost-sensitive learning (CSL) algorithms are based on the assumption that all involved costs can be transformed into a unified unit, called as homogeneous assumption of costs. While it is a challenge to construct many suitable transformation functions for the costs with diverse units, this paper designs a heterogeneous-cost sensitive learning (HCSL) algorithm to make split attribute selection more effective. This paper first proposes an efficient method of reducing the heterogeneity caused by both cost mechanisms and attribute information. And then, all heterogeneous costs with attribution information together are incorporated into the process of split attribute selection, called as HCAI-based split attribute selection. Third, the over-fitting is tackled by designing a simple and effective smoothing strategy, so as to build cost-sensitive decision tree classifiers with the HCSL algorithm. Experiments are conducted to evaluate the proposed HCSL algorithm on six UCI datasets. Experimental results show that the proposed approach outperforms existing methods for handling the heterogeneity caused by cost mechanisms and attribute information.     

Experimental and numerical study on aerodynamic noise of outdoor unit of room air conditioner with different grilles

The aerodynamic and aeroacoustic performances of outdoor unit with two different types of grille have been investigated in present study. Experimental results indicate that the grille sharp will affect the flow rate and increase broadband noise level of outdoor unit. Based on noise generation mechanism and CFD simulation, vortex shedding noise model and inlet turbulence noise model are adopted to predict the broadband noise level of outdoor unit. When vortex shedding noise is concerned, the wake parameters should be calculated at 3 mm downstream of grille to achieve good accuracy. Inlet turbulence noise is generated from the interaction between blade wake and the grille, and plays less important role in present outdoor unit configuration. In comparison with experimental results, it is shown that the broadband noise prediction method could provide reasonable accuracy and the error between prediction and experiment is less than 1 dBA.     

腐蚀的电化学研究现状

基于电化学原理发展起来的电化学测试技术,如极化曲线分析法,交流阻抗分析法,电化学噪声分析法和Kelvin探针技术等,是研究腐蚀的重要手段,近些年有了很大的进展。掌握这些技术的原理及应用领域的进步,将有助于对腐蚀与防护技术的深入研究和开发。