构建“分合有度”的新型党政关系

党政关系是政治体制改革核心问题,也是执政党建设和改革的关键。目前和今后一个时期党政关系应该如何理顺调适?本文认为既不能走党政合一、以党代政的老路,也不宜勉强去党政分开。应该按照十六大提出的“依法执政”的路径,构建“有分有合、分合有度”的中国特色的新型党政关系。

分合有度:中国共产党领导下土地制度变革的100年

中国共产党成立以来,一直致力于国家建设、社会发展、民生改善,先后在农村实施土地改革、合作化运动等生产关系的变革,致力于将巩固国家政权与改善人民群众的生活同步推进。概括而言,土地或“分”或“合”,主要取决于生产关系必须符合生产力发展的要求、取决于不同生产力水平下对公平—效率的追求、取决于国家—农民—土地关系调整的状况。选择“分”或者“合”,需要按照相应条件的变化而变化,需要伴随生产力的发展不断调整生产关系。土地改革运动、合作化运动、“包产到户”“三权分置”改革都是在党的领导下变革土地制度的探索与实践,这些探索为加强党的领导、推进国家治理体系与治理能力现代化、提高人民生活水平发挥着至关重要的作用,也为我国进一步深化改革积累了经验。随着国家乡村振兴战略的全面实施,乡村无疑将成为未来发展的重点与热土,届时无论是发展效度、价值效度、治理效度均将进一步凸显。

Investigation on temperature field of unidirectional carbon fiber/epoxy composites during drilling process

The phenomenon of heat accumulation and transportation in the composite materials is a very typical and critical issue during drilling process.In this study,a three-dimensional temperature field prediction model is proposed using finite difference method,based on the partly homogenization hypothesis of material,to predict temperature field in the process of drilling unidirectional carbon fiber/epoxy(C/E)composites.According to the drilling feed motion,drilling process is divided into four stages to study the temperature distributing characteristics.The results show that the temperature distribution predicted by numerical study has a good agreement with the experimental results.The temperature increases with increasing the drilling depth,and the burn phenomena is observed due to the heat accumulation,especially at the drill exit.Due to the fiber orientation,an elliptical shape of the temperature field along the direction is found for both numerical and experimental studies of C/E composites drilling process.

Depth Classification of Underwater Targets Based on Complex Acoustic Intensity of Normal Modes

In order to solve the problem of depth classification of the underwater target in a very low frequency acoustic field, the active component of cross spectra of particle pressure and horizontal velocity （ACCSPPHV） is adopted to distinguish the surface vessel and the underwater target. According to the effective depth of a Pekeris waveguide, the placing depth forecasting equations of passive vertical double vector hydrophones are proposed. Numerical examples show that when the sum of depths of two hydro- phones is the effective depth, the sign distribution of ACCSPPHV has nothing to do with horizontal distance; in addition, the sum of the first critical surface and the second critical surface is equal to the effective depth. By setting the first critical surface less than the difference between the effective water depth and the actual water depth, that is, the second critical surface is greater than the actual depth, the three positive and negative regions of the whole ocean volume are equivalent to two positive and negative regions and therefore the depth classification of the underwater target is obtained. Besides, when the 20 m water depth is taken as the first critical surface in the simulation of underwater targets （40 Hz, 50 Hz, and 60 Hz respectively）, the effectiveness of the algorithm and the cor- reemess of relevant conclusions are verified, and the analysis of the corresponding forecasting performance is conducted.

Stress distributions on crown-luting cement-substrate system with finite element method

The aim of this work is to analyze the stress distributions on a crown-luting cement-substrate system with a finite-element method in order to predict the likelihood of interfacial micro cracks, radial or circumferential cracks, delamination, fracture and delamination with torsion. The contact and layer interface stresses in elastic layered half-space indented by an elastic sphere were examined using finite element method. The model consists of crown, luting cement and substrate. The solutions were carried out for three different elastic moduli of luting cement. It was placed between the cement and the substrate as a middle layer and its elastic module was chosen lower than the elastic module of crown and higher than the elastic module of dentin. An axisymmetric finite element mesh was set up for the stress analysis. Stress distributions on the contact surface and the interfaces of crown-luting cement and luting cement-dentin have been investigated for three different values of luting cement by using ANSYS. The effects of the luting cement which has three different elastic moduli on the pressure distribution and the location of interfacial stresses of the multi-layer model have been examined. The mechanism of crack initiation in the interfaces and interracial delamination was also studied quantitatively. For each luting cement, the pressure distribution is similar at the contact zone. Stress discontinuities occur at the perfect bonding interfaces of the crown-luting cement and the substrate-luting cement. The maximum stress jumps are obtained for the highest and the lowest elastic module of the luting cement. In the crown-luting cement-substrate system, failures may initiate at crown-luting cement region for luting cement with the lowest elastic module value. In addition, failures at luting cement-substrate region may occur for luting cement with the highest elastic module. In the luting cement, the medium elastic module value is more suitable for stress distribution in crown-luting cement-substrate interfaces.

2D Finite Element Computer Analysis of Strength for Brazed Joint of Cemented Carbide and Silver Brazing Filler Metal

Brazing has a wide acceptance in industries and its simplicity in variety of application attracts more and more patronage. The strength of brazing joint determines the reliability of brazed engineering components. So the need to ascertain the reliability or to predict its failure （without some destructive testing） becomes high even with a computer aided analysis using the Finite Element Analysis. Here, we have employed the services of FEA software, Abaqus CAE, as a tool for the computer calculation to investigate a joint case of cemented carbide brazed with silver-based filler metal. In this paper, 2D analysis has been adopted because the thickness of the material （in 2D） does not influence the final calculation results. We have applied constant loading and constant boundary condition to explore data from the elastic and plastic strain analysis through which we were able to predict the maximum joint strength with respect to the joint thickness. The pattern of the meshing was also significant. And the result could be transferable to a real-life field situation. The final results showed that there is an optimum thickness of the filler metal with the maximum strength which matches that obtained from experiment.

Comparative Study on the Antibacterial Activity of Fresh and Fallen Leaves of Terminalia catappa L.

In the work reported here, the potential of different methods （cold and hot water, and ethanolic） of extraction of Indian almond （Terminalia catappa L.）, fresh and fallen leaves as an anti-bacterial agent was investigated. The hot water extract did not show any spectrum of activity against the selected bacteria while the cold water extract showed slight antibacterial activity suggesting that the effective components are heat labile. The ethanolic extracts of the leaves have higher antibiotic spectrum of activity than the cold water extract showing ethanol to be a better solvent in extracting the effective component. The fallen leaves seem to have a higher concentration of the effective component against the bacteria while ethanolic extract of the fresh leaves have similar spectrum of activity to Ciprofloxacin and Nitrofuratoin. These suggest that some effective components are lost when leaves fall off while some seem to increase in concentration. Fresh and fallen leaves contain tannin and flavonoids. In addition, the fallen leaves contain flavones. This might be responsible for the higher activity of fallen leaves extract observed against Pseudomonas and Staphylococcus spp. in our study. Combined use of extracts from fresh and fallen leaves broadened the spectrum of activity.

Application of complete ensemble intrinsic time-scale decomposition and least-square SVM optimized using hybrid DE and PSO to fault diagnosis of diesel engines

Targeting the mode-mixing problem of intrinsic time-scale decomposition （ITD） and the parameter optimization problem of least-square support vector machine （LSSVM）, we propose a novel approach based on complete ensemble intrinsic time-scale decomposition （CEITD） and LSSVM optimized by the hybrid differential evolution and particle swarm optimization （HDEPSO） algorithm for the identification of the fault in a diesel engine. The approach consists mainly of three stages. First, to solve the mode-mixing problem of ITD, a novel CEITD method is proposed. Then the CEITD method is used to decompose the nonstationary vibration signal into a set of stationary proper rotation components （PRCs） and a residual signal. Second, three typical types of time-frequency features, namely singular values, PRCs energy and energy entropy, and AR model parameters, are extracted from the first several PRCs and used as the fault feature vectors. Finally, a HDEPSO algorithm is proposed for the parameter optimization of LSSVM, and the fault diagnosis results can be obtained by inputting the fault feature vectors into the HDEPSO-LSSVM classifier. Simulation and experimental results demonstrate that the proposed fault diagnosis approach can overcome the mode-mixing problem of ITD and accurately identify the fault patterns of diesel engines.