A comparison of pyrrolidide and picolinyl ester derivatives for the identification of fatty acids in natural samples by gas chromatography-mass spectrometry

The pyrrolidide and picolinyl ester derivatives of the fatty acids in two natural lipid samples rich in unsaturated fatty acids, pig testis lipids and cod liver oil were satisfactorily resolved on capillary columns of fused silica coated with stationary phases of varying polarity. The picolinyl esters, in particular, when subjected to gas chromatography-mass spectrometry on a column containing a cross-linked methyl silicone, gave distinctive mass spectra, which could be interpreted in terms of both the numbers and positions of the double bonds.     

Editor’s corner

Editor’s corner     

Ranking protective coatings: Laboratory vs. field experience

Environmentally protective coatings are used on a wide range of gas turbine components for survival in the harsh operating conditions of engines. A host of coatings are commercially available to protect hot-section components, ranging from simple aluminides to designer metallic overlays and ceramic thermal barrier coatings. A variety of coating-application processes are available, and they range from simple pack cementation processing to complex physical vapor deposition, which requires multimillion dollar facilities. Detailed databases are available for most coatings and coating/process combinations for a range of laboratory tests. Still, the analysis of components actually used in engines often yields surprises when compared against predicted coating behavior from laboratory testing. This paper highlights recent work to develop new laboratory tests that better simulate engine environments. Comparison of in-flight coating performance as well as industrial and factory engine testing on a range of hardware is presented along with laboratory predictions from standard testing and from recently developed cyclic burner-rig testing.     

The Hardware / Personnel Cost Relationship: Separating Fact from Fancy

Few MIS managers have not seen a diagram that depicts the relationship between falling hardware costs and rising personnel costs. This may be the most pervasive diagram in the DP industry, and the conclusions that are drawn from it vary —it has been cited in everything from justifications of user-friendly software to end-user productivity strategies. This article assesses the real relationship between hardware and personnel costs and shows that some very misleading conclusions are being based on this popularly perceived hardware/personnel cost relationship.     

Evolutionary search for understanding movement dynamics on mixed networks

This paper describes an approach to using evolutionary algorithms for reasoning about paths through network data. The paths investigated in the context of this research are functional paths wherein the characteristics (e.g., path length, morphology, location) of the path are integral to the objective purpose of the path. Using two datasets of combined surface and road networks, the research demonstrates how an evolutionary algorithm can be used to reason about functional paths. We present the algorithm approach, the parameters and fitness function that drive the functional aspects of the path, and an approach for using the algorithm to respond to dynamic changes in the search space. The results of the search process are presented in terms of the overall success based on the response of the search to variations in the environment and through the use of an occupancy grid characterizing the overall search process. The approach offers a great deal of flexibility over more conventional heuristic path finding approaches and offers additional perspective on dynamic network analysis.     

A Stochastic Vehicle Routing Problem with Travel Time Uncertainty: Trade-Off Between Cost and Customer Service

On-time shipment delivery is critical for just-in-time production and quick response logistics. Due to uncertainties in travel and service times, on-time arrival probability of vehicles at customer locations can not be ensured. Therefore, on-time shipment delivery is a challenging job for carriers in congested road networks. In this paper, such on-time shipment delivery problems are formulated as a stochastic vehicle routing problem with soft time windows under travel and service time uncertainties. A new stochastic programming model is proposed to minimize carrier’s total cost, while guaranteeing a minimum on-time arrival probability at each customer location. The aim of this model is to find a good trade-off between carrier’s total cost and customer service level. To solve the proposed model, an iterated tabu search heuristic algorithm was developed, incorporating a route reduction mechanism. A discrete approximation method is proposed for generating arrival time distributions of vehicles in the presence of time windows. Several numerical examples were conducted to demonstrate the applicability of the proposed model and solution algorithm.     

确保管道运输的泄漏检测技术

保证所有管道中石油从一端流向另一端不泄漏要比它的探测更加困难。比较图中的3个系统,可以看到这项技术在40多年来是如何逐步发展的。     

Estimating the lifetime utilization rate of radiotherapy in cancer patients: the Multicohort Current Utilization Table (MCUT) method

Extensive research has been carried out to establish the appropriate proportion of cancer patients requiring radiotherapy at some point during their illness. However, it is difficult to compare the actual rates against the appropriate rate, because calculating the actual rates requires life-long follow up of cancer patients. We have developed a method, referred to as the Multicohort Current Utilization Table (MCUT) method, to estimate the predicted lifetime utilization rates based on current medical practice. We implemented the method in SAS as a macro, and validated it by comparing the predicted and the actual utilization rates of radiotherapy in lung, breast, and prostate cancer cases diagnosed in Ontario, Canada. The MCUT method could be used to predict lifetime utilization rate of any medical services.     

Measuring information systems success: models,dimensions, measures,and interrelationships

Since DeLone and McLean (D&M) developed their model of IS success, there has been much research on the topic of success as well as extensions and tests of their model. Using the technique of a qualitative literature review, this research reviews 180 papers found in the academic literature for the period 1992–2007 dealing with some aspect of IS success. Using the six dimensions of the D&M model – system quality, information quality, service quality, use, user satisfaction, and net benefits – 90 empirical studies were examined and the results summarized. Measures for the six success constructs are described and 15 pairwise associations between the success constructs are analyzed. This work builds on the prior research related to IS success by summarizing the measures applied to the evaluation of IS success and by examining the relationships that comprise the D&M IS success model in both individual and organizational contexts.