侏罗纪厚煤层综放工作面设备选型及效果

介绍侏罗纪厚煤层综采放顶煤开采设备的选型原则、技术参考,设备配套使用效果,针对目前工作实际,展开相应讨论,并提出相关建议。     

Econometric Analysis of Managers' Judgements on the Determinants of the Financial Situation in Russia

The paper presents an econometric analysis of the determinants of the financial situation in Russian manufacturing. Official statistics in Russia are not reliable. This is why the analysis is based on business opinion surveys carried out within `The Russian Economic Barometer' long-term research programme for monitoring and investigation of the transition to the market in Russia. The new adaptive approach elaborated by the author of the paper is used to form a correct set of explanatory variables in regression equations. This approach is based on the comparison of the forecast abilities of alternative models with different sets of explanatory variables. Two periods are considered and compared: January 1993 to January 1995 and February 1995 to January 1998. Two variables, the diffusion index of output and the average order-book level, provide the best explanation of the managers' judgement regarding the financial situation in Russia for the first period. It was found that for the second period, the influence of the `output index' diminished. The main factors with which managers related a `good' financial situation in their enterprises were the sample average of order-book level, the stocks of finished goods, the index of order-book level, the index of output prices ratio, and the indebtedness to banks. All relationships are presented in the context of linear probability and logit models.     

Research on e-commerce transaction networks using multi-agent modelling and open application programming interface

We provide a formal definition of an e-commerce transaction network. Agent-based modelling is used to simulate e-commerce transaction networks. For real-world analysis, we studied the open application programming interfaces (APIs) from eBay and Taobao e-commerce websites and captured real transaction data. Pajek is used to visualise the agent relationships in the transaction network. We derived one-mode networks from the transaction network and analysed them using degree and betweenness centrality. Integrating multi-agent modelling, open APIs and social network analysis, we propose a new way to study large-scale e-commerce systems.     

Coloured Logic Petri Nets and analysis of their reachable trees

Logic Petri nets (LPNs) can describe and analyse the batch processing function and passing value indeterminacy in cooperative systems, and alleviate the state space explosion problem. However, the indeterminate data of logical output transitions cannot be described explicitly in LPNs. Therefore, Coloured Logic Petri nets (CLPNs) are defined in this paper. It can determine the indeterminate data of logic output transitions in LPNs, i.e., the indeterminate data can be represented definitely in CLPNs. A vector matching method is proposed to judge the enabling transitions and analyse CLPNs. From the marking equation and the proposed reachable tree generation algorithm of CLPNs, a reachable tree can be built, and reachable markings are calculated. The advantage of CLPNs can be shown based on the number of leaf nodes of the reachability tree, and CLPNs can solve the indeterminate data of logical output transitions. Finally, an example shows that CLPNs can further reduce the dimensionality of reachable markings.     

Money,random matching and endogenous growth: A quantitative analysis

In this study, we develop a search-and-matching monetary growth model to analyze the effects of inflation on economic growth and social welfare by introducing endogenous economic growth via capital externality into a two-sector search-and-matching model. We find that the channel through which inflation affects economic growth in the search-and-matching model is different from the traditional cash-in-advance model. To facilitate the calibration, we obtain an empirical estimate of the effects of inflation on economic growth using panel regressions. In the simulation analysis, we quantitatively evaluate the welfare effect of inflation in the search-and-matching endogenous growth model and compare it to a search-and-matching exogenous growth model. We find that the welfare effect of inflation is nonlinear in the endogenous growth model whereas it is linear in the exogenous growth model. Furthermore, we find that the welfare cost of inflation under endogenous growth is up to four times as large as the welfare cost of inflation under exogenous growth.     

Escape dynamics: A continuous-time approximation

We extend a continuous-time approximation approach to the analysis of escape dynamics in economic models with constant gain adaptive learning. This approach is based on the application of the results of continuous-time version of large deviations theory to the linear diffusion approximation of the original discrete-time dynamics under learning. We characterize escape dynamics by analytically deriving the most probable escape point and mean escape time. The approximation is tested on the Phelps problem of a government controlling inflation while adaptively learning a misspecified Phillips curve, studied previously by Sargent (1999) and Cho et al. (2002) (henceforth, CWS), among others. We compare our results with simulations extended to very low values of the constant gain and show that, for the lowest gains, our approach approximates simulations relatively well. We express reservations regarding the applicability of any approach based on large deviations theory to characterizing escape dynamics for economically plausible values of constant gain in the model of CWS when escapes are not rare. We show that for these values of the gain it is possible to derive first passage times for learning dynamics reduced to one dimension without resort to large deviations theory. This procedure delivers mean escape time results that fit the simulations closely. We explain inapplicability of large deviations theory by insufficient averaging near the point of self-confirming equilibrium for relatively large gains which makes escapes relatively frequent, suggest the changes which might help approaches based on the theory to work better in this gain interval, and describe a simple heuristic method for determining the range of constant gain values for which large deviations theory could be applicable.     

The substitutes condition and the lattice structure of the set of stable allocations

In the many-to-one matching model with contracts, I show that there is no restriction on preferences weaker than substitutable preferences which guarantees that the set of stable allocations is a lattice. Thus, when contracts are not substitutes, removing agents from the economy may decrease the payoffs to existing agents on both sides of the market.     

Learning in an estimated medium-scale DSGE model

We evaluate the empirical relevance of learning by private agents in an estimated medium-scale DSGE model. We replace the standard rational expectations assumption in the Smets and Wouters (2007) model by a constant-gain learning mechanism. If agents know the correct structure of the model and only learn about the parameters, both expectation mechanisms produce very similar results, and only the transition dynamics that are generated by specific initial beliefs seem to improve the fit. If, instead, agents use only a reduced information set in forming the perceived law of motion, the implied model dynamics change and, depending on the specification of the initial beliefs, the marginal likelihood of the model can improve significantly. These best-fitting models add additional persistence to the dynamics and this reduces the gap between the IRFs of the DSGE model and the more data-driven DSGE-VAR model. However, the learning dynamics do not systematically alter the estimated structural parameters related to the nominal and real frictions in the DSGE model.     

Deep habits and the cyclical behaviour of equilibrium unemployment and vacancies

We extend the standard textbook search and matching model by introducing deep habits in consumption. This assumption generates amplification in the response of labour market variables to technology shocks by producing endogenous countercyclical mark-ups. The cyclical fluctuations of vacancies and unemployment in our model can replicate those observed in the US data, with labour market tightness being 20 times more volatile than consumption. Vacancies display a hump-shaped response to technology shocks and the numerical simulations generate an artificial Beveridge curve that is in line with the data. Our model preserves the assumption of fully flexible wages for new hires and the calibration is consistent with the estimated elasticity of unemployment to unemployment benefits. Finally, we show that in contrast to models with exogenous mark-up shocks, the deep habits model does not require an implausible variation in the elasticity of demand to match the volatility of labour market variables, and the cyclical properties of the mark-up are in line with empirical evidence.     

大功率电子发射管的正确使用及延长其寿命的方法

大功率电子发射管广泛应用于广播电视发射设备及其他电子通信设备,文章介绍了采用冷打压老炼、灯丝电压调整、谐振匹配等技术方法延长电子管的使用寿命。