无线视频服务器在ADSP-BF5614的研究与实现

通过对视频服务器相关资料的研究,提出了一种基于ADI公司专用DSP芯片ADSP-BF561的无线视频服务器的解决方案。硬件设计采用SAA7113芯片完成输入视频A/D转换,以ADSP-BF561芯片为核心硬件平台实现视频压缩编码,利用相应外围设备实现网络控制和传输。该方案由于使用了H.264视频编码标准、G729音频编码标准和基于CDMA1X无线网络技术的CDMA无线网络作为音视频数据的传输途径,具有良好的稳定性和可实现性。     

Provincial Conditional Income Convergence in China, 1953-1997: A Panel Data Approach

This paper examines the tendency towards income convergence among China's main provinces during the two periods: the pre-reform period 1953-1977 and the reform period 1978-1997 using the framework of the Solow growth model. The panel data method accounts for not only province-specific initial technology level but also the heterogeneity of the technological progress rate between the fast-growing coastal and interior provinces. Estimation problems of weak instruments and endogeneity are addressed by the use of a system generalized method of moments (GMM) estimator. The main empirical finding is that there is a system-wide income divergence during the reform period because the coastal provinces do not share a common technology progress rate with the interior provinces.     

ESTIMATION OF DISCRETE CHOICE MODELS WITH MINIMAL VARIATION OF ALTERNATIVE-SPECIFIC VARIABLES

The paper states conditions for minimal variation within the explanatory variables such that the maximum likelihood estimate of the coefficient vector in the discrete choice logit model is unique. Special emphasis is given to the case that (almost) all individuals observe the same set of alternative-specific explanatory variables. The aspect of 'experimental design' in discrete choice models is discussed.     

IMPROVING THE NUMERICAL TECHNIQUE FOR COMPUTING THE ACCUMULATED DISTRIBUTION OF A QUADRATIC FORM IN NORMAL VARIABLES

This paper is concerned with the technique of numerically evaluating the cumulative distribution function of a quadratic form in normal variables. The efficiency of two new truncation bounds and all existing truncation bounds are investigated. We also find that the suggestion in the literature for further splitting truncation errors might reduce computational efficiency, and the optimum splitting rate could be different in different situations. A practical solution is provided. The paper also discusses a modified secant algorithm for finding the critical value of the distribution at any given significance level.     

Voluntary income sharing and the design of unemployment insurance

This paper uses a model of search unemployment to discuss the interaction between publicly provided insurance and informal insurance through voluntary income sharing, e.g., between spouses. Income sharing reduces the optimal level of public unemployment insurance. While it is always individually rational for partners to share income, the effect of voluntary income sharing on welfare will be negative unless partners can either observe each other's search behavior or are sufficiently altruistic towards each other. The model is also used to examine a family-based policy. The welfare gains from using such policy are argued to be small. Received: 14 December 2000/Accepted: 5 November 2001     

Enclaves, neighbourhood effects and employment outcomes: Ethnic minorities in England and Wales

Ethnic minorities in England and Wales are spatially concentrated in relatively-deprived urban areas. Both geographic clustering and the economic characteristics of ethnically-concentrated neighbourhoods can impact upon the opportunities and constraints facing residents of such areas. This paper explores the relationship between the existence of enclaves and the employment prospects of ethnic minorities in England and Wales. It is shown that there is considerable spatial variation in employment outcomes. There is a lower incidence of self-employment in more ethnically-concentrated urban areas, which contradicts the view of ethnic entrepreneurship as an enclave phenomenon. Unemployment rates are also higher for minorities living in more concentrated areas. Enclaves in England and Wales do not appear to offer many economic benefits to minority individuals. Received: 31 December 1999/Accepted: 27 November 2000     

On the detection of changes in autoregressive time series I. Asymptotics

Various test statistics are discussed which can be used for detecting changes in the parameters of an autoregressive time series. In this first part of our study, the limiting behavior of the test statistics is derived under the null hypothesis of no change as well as under alternatives. In a forthcoming second part of our investigation, these asymptotic results will be compared to some corresponding bootstrap procedures, and a small simulation study will be conducted.     

Family size and optimal income taxation

This paper studies the role of family size in the design of optimal income taxation. We consider a second best setting where the government observes the number of children and the income of the parents but not their productivity. With a linear tax schedule the marginal tax rate is shown to decrease with the number of children, while the relationship between the demogrant and family size appears to be ambiguous. With two ability levels, optimal non-linear income tax implies zero marginal tax rates for the higher ability parents; low ability parents have positive marginal tax rates that decrease with family size. Received: 4 September 2000/Accepted: 17 May 2001     

Arbeitsmarktforschung und Arbeitsmarktstatistik aus der Sicht der wirtschaftspolitischen Beratung: Erfahrungen und Perspektiven

Zusammenfassung: Dieser Beitrag beleuchtet aus der Sicht der wirtschaftspolitischen Beratung einige Anforderungen an die Arbeitsmarkt?konomik und Arbeitsmarktstatistik. Drei Bereiche werden angesprochen: die Arbeitslosenstatistik, die Tariflohnpolitik und die aktive Arbeitsmarktpolitik. Dabei werden zun?chst die Bemühungen hinsichtlich einer realistischeren Erfassung der Unterbesch?ftigung gewürdigt, zugleich aber Hinweise auf Verbesserungsm?glichkeiten gegeben. Anforderungen an die amtliche Statistik ergeben sich des Weiteren hinsichtlich der Tarifentgelte. In diesem Zusammenhang wird die Umsetzung der Erkenntnisse der Arbeitsmarkt?konomik in eine lohnpolitische Orientierungshilfe skizziert. Schlie?lich erfolgt eine kritische Einsch?tzung des Erfolgs der aktiven Arbeitsmarktpolitik, wobei eine zunehmende Willigkeit zur Bereitstellung der für die Evaluation erforderlichen Daten konstatiert werden kann.

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Summary: This paper deals with three demands on labor economics and labor statistics put forward from the point of view of an advisor to economic policy. Despite several improvements of unemployment statistics, a lot of work remains to be done. With respect to wage policy attempts by the German Council of Economic Experts are discussed how to formulate a guidance for wage policy both on scientific grounds and understandable by the public. Finally, a critical assessment of active labor market policies is presented together with a plea for adequate individual data in order to carry out a sound evaluation of these policies.

* Vortrag für die „Statistische Woche“, die Jahrestagung der Deutschen Statistischen Gesellschaft am 20. September 2004 in Frankfurt/Main. Der Vortragsstil wurde beibehalten. Die hier vorgetragenen Auffassungen liegen allein in der Verantwortung des Autors und stellen nicht notwendigerweise die Auffassungen anderer Institutionen dar. Ich danke Bernd Fitzenberger (Universit?t Frankfurt/Main und ZEW), Joachim M?ller (Universit?t Regensburg), Bernhard Boockmann und Tobias Hagen (ZEW), Irmtraud Beuerlein und Dirk Heinlein (Statistisches Bundesamt) für hilfreiche Kommentare und Anregungen. Verbleibende M?ngel gehen—leider—zu meinen Lasten.     

Characterization of minimum aberration mixed factorials in terms of consulting designs

In this paper, by introducing a concept of consulting design and based on the connection between factorial design theory and coding theory, we obtain combinatorial identities that relate the wordlength pattern of a regular mixed factorial design to that of its consulting design. According to these identities, we further-more establish the general and unified rules for identifying minimum aberration mixed factorial designs through their consulting designs. It is an improvement and generalization of the results in Mukerjee and Wu (2001). This paper is supported by NNSF of China grant No. 10171051 and RFDP grant No. 1999005512.