Using DEA models to jointly estimate service quality perception and profitability – Evidence from international airports

With increasing competition between airports and a growing share of non-aeronautical revenues, particularly at large international hubs, perceived quality and consumer satisfaction have not only become a key focus of management but potentially the most important tool to achieve or maintain a competitive advantage. However, in the long run stakeholders aim for profit maximisation and it has been shown for other parts of the aviation supply chain that quality does significantly impact on profitability. In this paper we aim to investigate whether perceived airport quality has an impact on airport profit margins. We further apply two-stage Data Envelopment Analysis (DEA) models to estimate a single efficiency measure that combines the potentially conflicting indicators of perceived service quality and profitability for the airport context. We also identify determinants of the jointly estimated single quality/profitability measure.     

Network sensor health problem

Many existing studies on the sensor health problem determine an individual sensor’s health status based on the statistical characteristics of collected data by the sensor. In this research, we study the sensor health problem at the network level, which is referred to as the network sensor health problem. First, based on the conservation principle of daily flows in a network, we separate all links into base links and non-base links, such that the flows on the latter can be calculated from those on the former. In reality, the network flow conservation principle can be violated due to the existence of unhealthy sensors. Then we define the least inconsistent base set of links as those that minimize the sum of squares of the differences between observed and calculated flows on non-base links. But such least inconsistent base sets may not be unique in a general road network. Finally we define the health index of an individual sensor as the frequency that it appears in all of the least inconsistent base sets. Intuitively, a lower health index suggests that the corresponding sensor is more likely to be unhealthy. We present the brute force method to find all least inconsistent base sets and calculate the health indices. We also propose a greedy search algorithm to calculate the approximate health indices more efficiently. We solve the network sensor health problem for a real-world example with 16 nodes and 30 links, among which 18 links are monitored with loop detectors. Using daily traffic count data from the Caltrans Performance Measurement System (PeMS) database, we use both the brute-force and greedy search methods to calculate the health indices for all the sensors. We find that all the four sensors flagged as unhealthy (high value) by PeMS have the lowest health indices. This confirms that a sensor with a lower health index is more likely to be unhealthy. Therefore, we can use such health indices to determine the relative reliability of different sensors’ data and prioritize the maintenance of sensors.     

Efficient contracting and incentive agreements between regulators and bus operators: The influence of risk preferences of contracting agents on contract choice

Contracts that govern transactions between regulators and operators are an important feature of service delivery in public transport. This paper reviews the literature on efficient contracting in general and its application to public transport contracts and found little empirical evidence on the influence of risk preferences of contracting agents on contract choice, a fundamental premise of classical contracting theory. Departing from the existing literature, this paper develops a choice experiment to study public transport operators’ preferences for different contractual forms. People involved in the public transport industry across Australia are invited to do the survey but the respondents are mainly bus operators in New South Wales. The respondents are offered two hypothetical contracts with different risk profiles and incentives and asked to indicate their preferences as well as their acceptance to provide the services under the contract they prefer. A non-linear scaled multinomial logit model is estimated to establish the role of risk allocation on contract preference of bus operators and the optimal amount of risks and incentives, conditioned on the operators’ attitude towards risk. The results help authorities design performance-based contracts to obtain their objectives while maintaining the operators’ level of satisfaction.     

Qualitative evaluation study of urban shared spaces in New Zealand

This paper presents the findings of a qualitative analysis using on-street perception and expert interview surveys of city centre streets that have been transformed into shared spaces in Auckland, New Zealand. The principal purpose was to investigate how well the shared streets performed, especially in relation to movement, access and place functions. The shared space sites at the Elliott, Lorne and Fort Street areas were measured against the performance criteria of Placemaking, Pedestrian Focus, Vehicle Behaviour Change, Economic Impetus and Safety for all users. On-street perception surveys totalling 360 responses (120 per site) were used in this study, together with an additional set of 40 responses from a survey of a control site in O’Connell Street that remained as a traditional street. Fifteen professionals with background in transportation and urban planning participated in semi-structured expert interviews. The main results of the Median Perception Ratings from the on-street surveys confirmed that the shared spaces generally performed positively. The statistical analysis revealed that the performance criteria of ‘Pedestrian’ and ‘Safety’ had a commanding influence over the other performance measures, and with the interconnectivity of the five objectives the perceived success of the urban shared spaces.     

Environmental effect of CI engine using microalgae methyl ester with doped nano additives

Algae are organisms that grow in marine environments and use carbon dioxide and light to create bio-mass. There are two groupings of algae: microalgae and macroalgae. Macroalgae are the large, multi-cellular algae often seen growing in ponds. Microalgae, on the other hand, are tiny, unicellular algae that normally grow in suspension within a body of water. Algae oil from microalgae has the possible to become a sustainable fuel source as biodiesel. Microalgae are produced through photosynthesis by utilizing sunlight, water, carbon dioxide and other nutrients. The Botryococcus braunii algal oil was extracted by mechanical extraction method. The transesterification reaction of Botryococcus braunii algal oil with methanol and base catalyst was used for the production of biodiesel. The samples B20 were prepared for each methyl ester obtained from Botryococcus braunii algal oil separately and then the doping of TiO₂ and SiO₂ nanoparticles were added to the each B20 blend samples at a dosage of 50 ppm and 100 ppm with an aid of ultrasonicator. Moreover, in the absence of any engine modifications, the performance and emission characteristics of those blend samples have been investigated from the experimentally measured values such as density, viscosity, calorific value, etc. while the engine performance was also analyzed through the parameters like BSFC, BTH, exhaust emission of CO, HC, NOx and CO₂. The experimental results reveal that the use of biodiesel blend with nano additives in diesel engine has exhibited good improvement in performance characteristic and reduction in exhaust emissions.     

沥青混合料中掺加聚合物纤维的试验研究

纤维对沥青混合料具有加筋、分散、稳定、吸附沥青和增粘等作用,对防止沥青析漏的功效较好。文章通过对掺加聚合物纤维的沥青混合料进行试验研究,得出在沥青混合料中掺加聚合物纤维可提高路用性能的结论。     

Adelaide bus service reform: Impacts, achievements and lessons

Adelaide's bus system has been transformed from a government monopoly operation to a competitively tendered system with services provided by private operators under contract. The ‘Adelaide model’ has unique features, and has been considered in several international reviews of urban bus service procurement. The paper reviews the experience in Adelaide up to 2006/07. It updates previous evidence that focused on technical efficiency impacts. It particularly examines the development of the system to address allocative efficiency, in terms of the quantity, quality and market orientation of the services provided, and the consequent effects on patronage.     

新型环氧沥青混合料（N-EA）和粘结剂性能试验评价研究

对一种新型研发的环氧沥青混合料（N -EA）和粘结剂进行了性能试验评价，对该环氧沥青混合料进行马歇尔稳定度、车辙、小梁弯曲、疲劳试验，以及环氧树脂粘结层拉拔试验，并与当前应用较多的日本 TAF环氧沥青和美国 ChemCo环氧沥青混合料的试验性能对比分析，结果显示这种新型研发的环氧沥青混合料和粘结剂具有良好的性能。     

高性能水泥基吸声材料

根据铁路噪声的频谱特性,针对高性能水泥基吸声材料的制成工艺、吸声性能以及力学性能进行研究。高性能水泥基吸声材料以水泥作为主要胶结材料,以膨胀珍珠岩为骨料,采用二维压力挤压成型。其基本配合比采用胶结剂∶孔结剂∶骨料∶水=5∶1∶45∶2.5(体积比)。利用水泥水化初期的可塑特性,通过孔结剂调整水泥基胶结体的孔隙特性,使高性能水泥基吸声材料形成多孔且在一定集域中连通的类絮状结构,从而使其具有良好的吸声性能。检测结果表明,该吸声材料的吸声系数大于0.8,达到了一等吸声制品的要求,同时其力学、耐候和耐久性能良好。     

可调式自由面减摇水舱的实船性能

通过对海洋工程船“新润3” 号的实船测试,获得了减摇水舱开启和关闭两种状态下的船舶横摇数据,比较准确地评估了不同海况下可调式自由面减摇水舱的减摇效果。进一步将实测减摇数据与理论预报结果对比,验证了理论预报方法的有效性和局限性。研究表明,减摇水舱的性能不仅仅取决于自由液面的面积大小和水位高低,也同样受制于舱顶的高度,有必要在设计和预报过程中予以充分考虑。