基于 BP 神经网络的唐山房价预测

2014年以来，全国房地产市场形势错综复杂。虽然大多数城市房价继续上涨，但相对去年高歌猛进的涨势，今年上半年的房价上涨温和，涨幅明显收窄，环比下降的城市数不断增多。未来房价的走势众说纷纭，结合唐山市的具体情况，利用B P神经网络对唐山2014年的房价做出预测。     

Does it pay to be eco? The mediating role of competitive benefits and the effect of ISO14001

Eco-innovation has become an important instrument to help companies reduce their environmental impact and gain a competitive advantage in increasingly competitive environments. Despite recent research conducted in this field, findings concerning the relationship between eco-innovation and firm performance remain conflicting, inconclusive and incomplete. This study aimed to clarify this relationship by incorporating competitive benefits as a mediator between eco-innovation and firm performance. Three core questions are examined: How does eco-innovation influence competitive benefits and firm performance? Do competitive benefits mediate the relationship between eco-innovation and firm performance? How does ISO14001 influence competitive benefits and firm performance? The study finds that competitive benefits mediate and strengthen the relationship between eco-innovation and firm performance. In addition, the results reveal that ISO14001 positively affects competitive benefits and thus leads to greater competitive benefits, while the association between ISO14001 and firm performance is not found to be statistically significant. The paper concludes with a discussion of implications for policy makers and companies, limitations, and future research directions.     

Produktdiversifizierung und Unternehmenserfolg: Nutzung der Forschungsdatenzentren der Statistischen ?mter

Zusammenfassung: Im Rahmen seiner industrie?konomischen Forschung beabsichtigt das DIW Berlin das Verhalten von Unternehmen auf den Produktm?rkten intensiver zu analysieren. In einem ersten Schritt soll der Zusammenhang zwischen Produktdiversifizierung, der Einführung neuer Produkte und dem Erfolg von Unternehmen im verarbeitenden Gewerbe untersucht werden. Dies soll mit Hilfe einer ?konometrischen Panelanalyse auf der Grundlage von Mikrodaten von Unternehmen erfolgen. Statt des in der Arbeitsmarktforschung üblichen Employer-Employee Datensatzes wird für diesen Zweck ein Producer-Product Datensatz ben?tigt. Erstmals sollen diese Mikrodaten im Rahmen einer Panelanalyse durch die Forschung ausgewertet werden. Dabei werden zwei getrennt durchgeführte Erhebungen, die Kostenstrukturerhebung und die Produktionserhebung, für einzelne Unternehmen zusammengefasst. M?glich wird dieses Forschungsvorhaben durch die Nutzung des auf Empfehlung der Kommission zur Verbesserung der informationellen Infrastruktur neu eingerichteten Forschungsdatenzentrums (FDZ). Das vorliegende Papier berichtet über das Forschungskonzept und die bisher erfolgten Schritte bei der Nutzung der Forschungsdatenzentren des Bundes und der L?nder am regionalen Standort Berlin.

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Summary: For a better understanding of the strategies of firms on their product markets, the DIW Berlin intends to intensify the analysis on the relationship between product diversification, including the introduction of new products and the success of firms. It is planned to do this by applying econometric panel methods on micro level data for German manufacturing enterprises. For this objective, it is necessary to create a producer-product database. This affords the merging of two different datasets of the system of surveys in manufacturing for Germany. The cost structure survey supplies information on the operating surplus of individual firms, while the production survey supplies the information on the goods produced by these firms. Conducting such an ambitious project has now been made possible in using the newly installed Research Data Centres (FDZ) for Germany. This paper gives an overview on the research project and on first experiences with the use of the local Research Data Centre in Berlin.

     

Asymptotic Throughput in Discrete‐Time Cyclic Networks with Queue‐Length‐Dependent Service Rates

Abstract

For a discrete‐time closed cyclic network of single server queues whose service rates are non‐decreasing in the queue length, we compute the queue‐length distribution at each node in terms of throughputs of related networks. For the asymptotic analysis, we consider sequences of networks where the number of nodes grows to infinity, service rates are taken only from a fixed finite set of non‐decreasing sequences, the ratio of customers to nodes has a limit, and the proportion of nodes for each possible service‐rate sequence has a limit. Under these assumptions, the asymptotic throughput exists and is calculated explicitly. Furthermore, the asymptotic queue‐length distribution at any node can be obtained in terms of the asymptotic throughput. The asymptotic throughput, regarded as a function of the limiting customer‐to‐node ratio, is strictly increasing for ratios up to a threshold value (possibly infinite) and is constant thereafter. For ratios less than the threshold, the asymptotic queue‐length distribution at each node has finite moments of all orders. However, at or above the threshold, bottlenecks (nodes with asymptotically‐infinite mean queue length) do occur, and we completely characterize such nodes.     

Is there early take-off phenomenon in diffusion of IP-based telecommunications services?

Traditionally, the diffusion of telecommunications services has been considerably affected by the presence of critical mass and network externalities, and thus has shown the so-called “late take-off” phenomenon. However, as telecommunications networks evolve from circuit switching to packet switching, especially IP networks, and thus enabling diverse new services, it seems these traditional telecommunications diffusion patterns are changing. By comparing the diffusion of IP-based services with those of circuit-based services and durable goods, we have found the late take-off phenomenon is not involved in the diffusion of newly introduced IP-based services. Moreover, we concluded that the diffusion of IP-based services is much faster than that of durable goods, thus showing an “early take-off” phenomenon. Based on this empirical result, we suggest that telcos (telecommunications companies) and (ISPs) Internet service providers should pay as much attention to the growth stage as the introduction stage in their development, in order for their IP-based services to be successful in the market.     

Nonparametric estimation of a survival function under progressive Type-I multistage censoring

Failure time data subject to three progressive Type-I multistage censoring schemes are studied. Product limit estimators are proposed for the estimation of the survival function. It is shown that the resulting estimators are asymptotically equivalent to the corresponding estimators where the data are subject to a random iid right censoring scheme. Many well-known results on confidence bands and tests for randomly right censored data hold for these progressive censoring schemes.     

A skew logistic distribution as an alternative to the model of van Staden and King

The logistic distribution is a simple distribution possessing many useful properties and has been used extensively for analyzing growth. Recently, van Staden and King proposed a quantile-based skew logistic distribution. In this paper, we introduce an alternative skew logistic distribution. We then establish recurrence relations for the computation of the single and product moments of order statistics from the standard skew logistic distribution by using the moments of order statistics from the standard half logistic distribution. These enable an efficient computation of means, variances and covariances of order statistics from the skew logistic distibution for all sample sizes. The results become useful in determining the best linear unbiased estimators of the location and scale paramters of the skew logistic distribution. Finally, we provide an example to illustrate the usefulness of the developed model and then compare its fit with that provided by the model of van Staden and King.     

Social media and Web 2.0 for knowledge sharing in product design

Working collaboratively with internal and external partners (suppliers, customers and internal stakeholders) has been at the epicentre of product design. Knowledge sharing has been well recognised in this context. However, there is limited research that has addressed the role of social media/Web 2.0 in facilitating knowledge sharing for sense- and decision-making within product design. To address this gap, this study draws on the resource-based view (RBV) of the firm and two vignettes that relate to ‘collaborative co-design’ and ‘collaborative design-to-order’. We illustrate the role of social media/Web 2.0 in building knowledge sharing capabilities for sense- and decision-making for internal and external partners during product design. Limitations and further research into the use of social media/Web 2.0 are also discussed.     

Selecting better process based on difference statistic using double sampling plan

Supplier management plays an important role in the quality improvement process. Recently, supplier selection has received much attention in many production industries. In this paper, we propose a double sampling plan for selecting a better supplier comparing two suppliers with linear profiles. The difference test statistic based on the process yield index S_pkA is used to determine the optimal parameters of the proposed double sampling plan. The efficiency of the proposed sampling plan is compared with the existing single sampling plan.     

Incorporating Price and Replacement Purchases in New Product Diffusion Models for Consumer Durables*

The article presents theoretical and empirical research findings which incorporate price and replacement purchases in new product diffusion models. On the theoretical side, this paper characterizes, qualitatively, optimum pricing policies for new products. Possible entry of rivals is not considered, but repeat sales, cost learning dynamics and discounting of future profit streams are allowed. Theoretical research findings suggest that the inclusion of repeat purchases in the diffusion model significantly changes the derived optimal pricing policy even if replacements were not price dependent. On the empirical side, alternative first purchase and repeat purchase models have been estimated and compared using nonlinear procedures. The diffusion data analyzed is related to nine consumer durables. Empirical research findings suggest that, for the considered product categories, diffusion is basically an imitative process, price can affect first and replacement purchases, and unit production cost is a decreasing function of cumulative first purchases. Managerial implications of the research findings are also discussed.