数字化无模铸造一模多型工艺研究

为解决数字化无模铸造精密成形技术在多件、大批量生产中效率低下的问题,可采用一模多型工艺。以某型号机床转台为例,进行一模多型工艺研究。设计合理的浇注与分模面工艺,Pro CAST软件模拟结果证明,所设浇注工艺是可行的,采用数字化无模铸造精密成形机进行砂型加工,得到合格铸件。研究结果表明,一模多型工艺可提高加工效率,为数字化无模技术在多件、大批量铸件的生产中提供参考。

Analyses of Multiplicity and Stability Patterns of Agglomeration Controlled Precipitation with Both Primary and Secondary Nucleations

The possibility of multiplicity in an isothermal continuous mixed suspension-mixed product removalcrystallizer is explored using the bifurcation theory. A process involving agglomeration controlled precipitationis considered in which secondary nucleation occurs simultaneously with primary nucleation. The determinantequations for the existence of multiple steady states are developed and the multiplicity boundaries dependent on thephysical and kinetic properties and operational parameters of the process are obtained by resolving these determinantequations. The number of steady states in the precipitator for various multiplicity regions is determined and thelinear stability of these steady states is analyzed by using the Routh criterion.

A Unified Model of All Generalizations from the Jones Polynomial

From the basic properties of skein systems, we build a generalized tangle algebra (GTA). The elements of GTA are four basic tangles. There are three operations, which are connection, splicing and scalar multiplication. From GTA we derive two generalized recursion formulae (GRF) and prove the existence of a generalized skein relation which satisfies GRF. The obtained generalized skein relation epitomizes all generalizations from the Jones polynomial and thus forms a unified model. Two important topological parameters, twisting measure and loop values, appear explicitly in the expressions of the unified model, and this fact greatly simplifies the operations.

Estimation in the polynomial errors-in-variables model

Estimators are presented for the coefficients of the polynomial errors-in-variables (EV) model when replicated observations are taken at some experimental points. These estimators are shown to be strongly consistent under mild conditions.

Geologic characteristics of the Chang'E-3 exploration region

We present topographic, geomorphologic and compositional characteristics of a l°×l° （-660 km2） region centered near the landing site of Chang＇E-3 using the highest spatial resolution data available. We analyze the topography and slope using Digi- tal Terrain Model （DTM） generated from Terrain Camera （TC） images. The exploration region is overall relatively flat and the elevation difference is less than 300 m, and the slopes of 80% area are less than 5~. Impact craters in the exploration region are classified into four types based on their degradation states. We investigate the wrinkle ridges visible in the exploration region in detail using TC and Lunar Reconnaissance Orbiter （LRO） Narrow Angle Camera （NAC） images. We calculate FeO and TiO2 abundances using Multispectral Imager （MI） data, and confirm two basaltic units： the northern part belongs to Imbrian low-Ti/very-low-Ti mare basalts, and the southern part is Eratosthenian low-Ti/high-Ti mare basalts. Finally, we produce a ge- ological map and propose the geologic evolution of the exploration region. We also suggest several rover traverses to explore interesting targets and maximize the potential scientific output.

RELAXED CONDITIONS FOR CONSENSUS IN MULTI-AGENT COORDINATION

This paper proposes relaxed sufficient conditions for the consensus of multi-agent systems by the averaging protocols with time-varying system topology. Bidirectional information exchange between neighboring agents is considered and both the discrete-time and continuous-time consensus protocols are studied. It is shown that the consensus is reached if there exists an unbounded time sequence such that two agents who own the maximum and minimum states at each time instant in the sequence will be jointly connected at some future time. Further, this result is applied to the original nonlinear Vicsek model, and a sufficient condition for the heading consensus of the group with restricted initial conditions is obtained.

Developed ‘laminar’ bubbly flow with non-uniform bubble sizes

Bubbles with different sizes have different dynamic and kinetic behavior in a two-phase bubbly flow. A common two-fluid model based on the uniform bubble size assumption is not suitable for a bubbly flow with non-uniform bubble sizes. To deal with non-uniform bubbly flows, a multi-fluid model is established, with which bubbles are divided into several groups according to their sizes and a set of basic equations is derived for each group of bubbles with almost the same size. Through analyzing the bubble-bubble and bubble-pipe wall interactions, two new constitutive laws for the wall-force and pressure difference between the liquid phase and interface are developed to close the averaged basic equations. The respective phase distributions for each group of bubbles measured by a specially designed three-dimensional photographic method are used to check the model. Comparison between model-predicted values and experimental data shows that the model can describe laminar bubbly flow with non-uniform bubble sizes.

Output Consensus for Heterogeneous Nonlinear Multi-Agent Systems Based on T-S Fuzzy Model

In this paper, the output consensus problem of general heterogeneous nonlinear multi-agent systems subject to different disturbances is considered. A kind of Takagi-Sukeno fuzzy modeling method is used to describe the nonlinear agents' dynamics. Based on the model, a distributed fuzzy observer and controller are designed based on parallel distributed compensation scheme and internal reference models such that the heterogeneous nonlinear multi-agent systems can achieve output consensus. Then a necessary and sufficient condition is presented for the output consensus problem. And it is shown that the consensus trajectory of the global fuzzy model is determined by the network topology and the initial states of the internal reference models. Finally, some simulations are given to illustrate and verify the effectiveness of the proposed scheme.