Modeling target group heterogeneity in experimental consumer studies

Acceptance of a product by a consumer may result from a convoluted interplay between product attributes and individual characteristics of that consumer. Different methods that systematically combine product properties with consumer groups segmented on such characteristics have provided unprecedented insight, but ignore heterogeneity in acceptance within each consumer group. Although such knowledge is invaluable for targeted marketing, dedicated methods for consumer group heterogeneity are lacking. The authors aim to fill this gap by the Individual Differences (InD) method, which models differences between consumers within the same target group. The method scores the ‘diffusion’ within each group, shows how much each consumer contributes to that, and relates this information to product properties. Thereby also novel groups may be discovered, with attributes not covered in the consumer segmentation. The illustrative consumer study on apple juice reveals how young women differ in their price-consciousness and their acceptance on specific preparation technologies more than older women. Although men exhibit heterogeneity on the same product attributes, their mutual variability is considerably lower and they thereby form more homogeneous target groups.     

Development of a cross-section based streamflow routing package for MODFLOW

It is challenging to simulate stream-aquifer interactions for the wide channel streams with the existing stream routing packages of MODFLOW. To overcome this limitation, a Cross-Section streamflow Routing (CSR) package is developed to simulate the streamflow and the interaction between streams and aquifers for the stream with a width larger than the MODFLOW grid size. In the CSR package, streams are divided into stream segments which are formed by two consecutive cross-sections. A cross-section is described by a number of streambed points that determine the geometry and hydraulic properties of the streambed. The stream water depth and streamflow at the cross-sections are related by the Single Channel method, the Divided Channel method, a data table or a power function. A rapid algorithm is used to compute the submerged area of the MODFLOW grid. The streambed conductance of a grid cell is computed based on its submerged area, streambed hydraulic conductivity and thickness. Stream-aquifer seepage is subsequently estimated as the product of the streambed conductance and difference between the stream stage and groundwater hydraulic head. Stream-aquifer seepage is treated as lateral flow in the streamflow routing computation with the Muskingum-Cunge method or mass conservation method. A hypothetical problem is established to test the capabilities of the CSR package with steady- and transient-state models. The results compare favorably with the SFR2 package and the HEC-RAS model. However, significant difference in flood wave attenuation is observed between the CSR package and the SFR2 package. It proves that the CSR package is capable of simulating the variation of stream-aquifer interactions in both space and time efficiently. The CSR package represents a certain improvement over previous MODFLOW streamflow packages by providing the efficient cross-section based computation and the unique capability of simulating streambed heterogeneity in longitudinal and transverse directions.     

非均质灰岩储层可变模型测井评价

灰岩储层一般呈现较强的非均质性,主要表现在毫无规律的孔渗关系、模糊的物性与含油性关系。碎屑岩储层中常用的单一模型处理方法只适合具有统一孔喉结构类型的灰岩储层,无法保证整个非均质灰岩层段处理结果准确。为揭示灰岩孔隙结构与灰岩测井处理模型的对应关系,采用5M孔隙结构分类技术(以Micro-,Micro+,Meso-,Meso+,Macro为代号的5种孔喉结构类型),结合灰岩储层类型测井自动识别,实现了非均质灰岩储层类型与测井处理模型自动匹配的多模型测井处理技术。这种多模型的测井处理技术,相比常规方法更适合非均质灰岩储层测井解释。该方法已经在南海东部很多非均质灰岩油藏中得到应用,取得了较好的效果。     

Predicting construction firm performance: an empirical assessment of the differential impact between industry‐ and firm‐specific factors

It is obvious that the performance of firms hinges upon the dynamics of both industry‐ and firm‐specific factors. A less obvious, and perhaps a more important, line of inquiry is that to the extent that they have a bearing on firm performance, how much do these two groups of factors respectively predict firm performance? To date, performance differences among construction firms that stem from industry‐ and firm‐specific differential effect has remained largely unexplored. Using a dataset comprising 526 firms across various construction‐related sectors, the sector‐by‐sector firm performance variation that is attributable to the heterogeneity of both industry‐ and firm‐specific characteristics was empirically examined. That statistically significant results of different effect sizes are found indicates that although these factors are often assumed to be intertwined it is possible to study their respective impact on firm performance. Future studies could usefully replicate and extend this study to construction firms in other countries to further investigate what drives firm performance under different national, industry and firm contexts.     

Approximations for heterogeneous finite source queues

The exact solution for heterogeneous finite source queues involves a definition of state which is unmanageable for large customer numbers. Accordingly various approximations are considered in an attempt to obtain a simple but reasonably accurate solution. The approximations examine simplified definitions of state with a consequent reduction in the number of states and associated balance equations; one such approximation converts the heterogeneous problem to an equivalent homogeneous problem through either time or rate averaging the problem components. Applications include earthmoving, quarrying and open-cut mining operations where the plant frequently have different characteristics. The exponential solution in such cases is anticipated to provide a hower bound estimate on operation productivity, by analogy with the homogeneous case.     

Heterogeneous households and firms in an urban model with open space and agglomeration economies*

This paper develops a model with heterogeneous households and firms that can locate anywhere in the city. The main features of the model are household preferences for open space which depend on distance to the greenbelts at the city periphery, and agglomeration economies for firms. Numerical results show equilibrium location patterns, rents, and wages under different model specifications. Under most conditions, monocentric location patterns (where there is a higher concentration of firms in the centre zones compared to surrounding zones) are observed, but duocentric location patterns for firms can emerge if both open space values and travel costs are high.     

TC18钛合金在热变形过程中的组织不均匀现象

揭示了Ti-5Al-5Mo-5V-1Fe-1Cr合金在等温压缩过程中出现的组织不均匀现象。首先使用真空自耗炉制备出合金铸锭,而后进行热加工和热处理,使用热处理后的材料车削成圆柱形试样进行等温压缩试验,试样端面没有进行打磨、抛光处理,结果出现了严重的组织不均匀,在试样内部发现了轴对称分布的局部大变形区,这将增加材料受力时起裂的几率。并就该组织现象展开了研究。     

Aggregate effects and measuring regional dynamics

Empirical models of regional adjustment often control for aggregate effects when estimating the impact of region-specific shocks on local economies. It is, however, difficult to filter out the effects of aggregate shocks—such as oil shocks, uncertainty shocks, or national recessions—because the incidence of these shocks varies across space and time. We propose an improved econometric method to control for this form of spatiotemporal heterogeneity, thereby yielding more accurate estimation of the effects of local shocks on regional economies. Applying the method to US states, we find that labour demand shocks are mostly absorbed through changes in participation; the migration response to these shocks is limited; and recoveries are highly protracted     

Characterization and analysis about the heterogeneity of inclusions in a 500kg steel ball

The distribution and transfer mechanism of MnS inclusions are distinguished from the solute segregation in a 500 kg steel ball. The increase of MnS inclusions is obvious from the surface to the center of the steel ball, while the increase of solute content is slight. The massive MnS inclusions converge in the channel zone and in heterogeneous zones. During solidification, the interface tension drives MnS inclusions to the frontier of the dendritic zone. Some inclusions trapped may float to induce the channel zone. Solidification contraction tears such channel zone to attract more melt enriched with inclusions. Some inclusions converge in the extra-dendritic melt. At later solidification stage, solidification contraction dominates the macro-distribution of extra-dendritic melt to produce the heterogeneous zones.