Improvements to the structural condition index (SCI) for pavement structural evaluation at network level

Structural evaluation provides valuable information about the expected behaviour and response of pavements and can be used at the network level of pavement management to prioritise projects. The falling weight deflectometer (FWD) can be used to identify the beginning and end of management sections and group pavement sections with similar structural capacities. The structural condition index (SCI) was developed as a screening tool for the pavement network-level evaluation, and the FWD data are used to determine the SCI. For the successful implementation of the SCI concept at the network level, one of the critical issues is the accuracy of the index. This article evaluates the accuracy of the SCI and also discusses a concept and procedure how to improve the SCI and its algorithm for low-volume flexible pavements. A case study (Texas) illustrates that the original SCI algorithm underestimates the existing structural condition, resulting in overestimated treatments in the pavement maintenance and rehabilitation.     

A continuous screening procedure using the performance and surrogate variables

A continuous screening procedure interchangeably using the performance and surrogate variables is proposed. At the start of the inspection, the performance variable is measured for all items. As soon as i consecutive items are found to be free of defects, the surrogate variable is measured instead of the performance variable. If an item is rejected, the inspection based on the performance variable is resumed. All non-conforming items found in the inspection are either reworked or replaced with conforming items. The average outgoing quality (AOQ) expression is derived, and methods of finding the inspection procedure with a specified average outgoing quality limit (AOQL) are presented.     

Internal pressures and thermal pressure coefficients for solid polymers

The temperature and pressure dependence of the thermal pressure coefficient and internal pressure for eight polymer solids are calculated. The principal results are as follows: (1) The pressure dependence of the thermal pressure coefficient at constant temperature is relatively small. (2) For some solid polymers, as a function of temperature, a maximum in the thermal pressure coefficient is predicted in the solid region, and the temperatures corresponding to the maximum values are estimated. (3) For most solid polymers, the zeropressure internal pressure increases with increasing temperature over the entire temperature range to the glass transition temperature or the melting point. © 1995 John Wiley & Sons, Inc.     

Synthesis and materials characterization of Li2MnO3-LiCrO2 system nanocomposite electrode materials

A series of Li[Cr_xLi_(1−x)/3Mn_2(1−x)/3]O₂, (0.2 ≤ x ≤ 0.4) with nanocomposite structures was synthesized by a solution method with subsequent quenching. The sample structures were investigated by X-ray diffraction (Rietveld refinement), electron diffraction and HRTEM. According to co-indexed electron diffraction patterns and HRTEM images, Li[Cr_0.211Li_0.268Mn_0.520]O₂ was found to be composed of solid solution powders and Li[Cr_0.290Li_0.240Mn_0.470]O₂ and Li[Cr_0.338Li_0.225Mn_0.436]O₂ of nanocomposite powders indexed in monoclinic and hexagonal structure. Among the three compounds, the nanocomposite Li[Cr_0.290Li_0.240Mn_0.470]O₂ cathode prevented spinel-like structural transformation during cycling and delivered a good reversible capacity of about 195 mAh/g.     

Analyzing Enterprise Resource Planning System Implementation Success Factors in the Engineering–Construction Industry

Enterprise resource planning (ERP) systems offer many benefits to the engineering–construction industry. Many construction firms recognize the benefits of ERP system implementation; however, they still hesitate to adopt these systems due to high cost, uncertainties, and risks. This study identifies and analyzes critical factors that need to be considered to ensure successful ERP system implementation in the construction industry. First, this paper identifies the factors associated with the success and failure of ERP systems, and provides indicators to evaluate the success of such systems. Then, the paper develops an information system success model to analyze the relationships between factors and success indicators. Finally, the paper provides recommendations for successful ERP systems based on the analysis. The derived success factors should help senior managers in construction firms make better decisions and improve their business value by implementing the most effective EPR systems.     

Acquisition of a problem-solving skill: Levels of organization and use of working memory.

We examined the acquisition of a problem-solving skill at three levels of organization—strategy, subgoal, and operator—and investigated changes in temporary storage, manipulation of information, and coordination of multiple representations. 6 college students practiced minimizing the simulated cost of solving diagnostic problems with digital electronic circuits for approximately 50 hr (347 problems). Ss were tested on declarative knowledge, inferential skills at the subgoal level, and ability to solve problems during working memory tasks. The working memory tasks required retention of a preload, concurrent processing, or integration of displayed information with the contents of working memory. The data support the view that restructuring is goal sensitive and strategic. The results suggest a multiple-level analysis of skill acquisition in which practice allows strategic restructuring of cognitive processes at 3 levels of organization. Implications for models of skill acquisition and working memory are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multispectral image restoration with multisensors

A procedure is advanced to restore a single color image, which has been degraded by a linear shift-invariant blur in the presence of additive stationary noise. Four sensors are needed, followed by the application of the RGB-to-YIQ transformation. Subsequently, one three-dimensional (3D) Wiener filter on a sequence of two luminance component images and two two-dimensional (2D) Wiener filters on each of the two chrominance component images are needed. For the procedure to be successful, the imposition of a strongly coprime condition on the wavenumber response of two distinct sensor blur functions is necessary. The resulting well-conditioned problem is shown to provide improved restoration over the decorrelated component and the independent channel restoration methods, each of which uses one sensor for each of the three primary color components     

PCS智能柱塞举升技术在户部寨气田的研究及应用

户部寨气田部分区块气井在投产初期就表现出高压低渗、低产出水的特征，已难以维持正常连续带液生产，经常积液停产。针对这些气井生产特征，在复线气举(套压太高)无法实施的情况下，先后开展了小油管、泡沫排液采气等工艺技术，但均未能奏效。在深入调查研究的基础上，开展了将油井上应用较为成熟的PCS智能柱塞举升技术引入这些气井上的试验。通过认真分析这些气井的静动态资料，并结合气井实际井筒工况，制定了合理的实施方案和施工参数，并调试运行成功。应用该技术后，在并无任何外来动力举升的情况下，实现了间歇带液生产的目的，解决了这些气井长期带液能力不足的难题，提高了该区块乃至整个气田的储量动用程度，为其它类似气井的开采提供了有益的借鉴。     

A note on spark bubble drop-on-demand droplet generation: simulation and experiment

The fluid dynamics of the spark bubble-generated droplet is studied both experimentally and numerically. The emphasis is especially on the droplet behavior after pinch-off. Commercial inkjet printers often produce satellite droplets along with parent droplets which are not desirable from the viewpoint of printing efficiency. Furthermore, standard drop-on-demand droplet generators are normally restricted to the generation of droplets with the same size as the nozzle diameter. In the spark bubble droplet generation method, a spark-generated bubble induces droplet formation through a hole in a solid surface separating the liquid and air interfaces. Immediately after ignition occurs, a bubble forms and creates pressure waves as it expands and contracts in a nonsymmetrical fashion. These pressure waves, depending on the geometries of the bubble location, plate, and hole may cause a single droplet smaller than the plate aperture to form and break up. In this article, a combined numerical and experimental study has been conducted to investigate the droplet behavior created in this manner. A high-speed camera is utilized to capture the droplet formation process. The numerical simulations have been carried out using the boundary integral spatial solution coupled with the time integration, i.e., a mixed Eulerian–Lagrangian approach. There is reasonable agreement between the simulations and experiment.