Improving the performance of model-order selection criteria by partial-model selection search

The traditional searching method for model-order selection in linear regression is a nested full-parameters-set searching procedure over the desired orders, which we call full-model order selection. On the other hand, a method for model-selection searches for the best sub-model within each order. In this paper, we propose using the model-selection searching method for model-order selection, which we call partial-model order selection. We show by simulations that the proposed searching method gives better accuracies than the traditional one, especially for low signal-to-noise ratios over a wide range of model-order selection criteria (both information theoretic based and bootstrap-based). Also, we show that for some models the performance of the bootstrap-based criterion improves significantly by using the proposed partial-model selection searching method. Index Terms— Model order estimation, model selection, information theoretic criteria, bootstrap 1. INTRODUCTION Several model-order selection criteria can be applied to find the optimal order. Some of the more commonly used information theoretic-based procedures include Akaike’s information criterion (AIC) [1], corrected Akaike (AICc) [2], minimum description length (MDL) [3], normalized maximum likelihood (NML) [4], Hannan-Quinn criterion (HQC) [5], conditional model-order estimation (CME) [6], and the efficient detection criterion (EDC) [7]. From a practical point of view, it is difficult to decide which model order selection criterion to use. Many of them perform reasonably well when the signal-to-noise ratio (SNR) is high. The discrepancies in their performance, however, become more evident when the SNR is low. In those situations, the performance of the given technique is not only determined by the model structure (say a polynomial trend versus a Fourier series) but, more importantly, by the relative values of the parameters within the model. This makes the comparison between the model-order selection algorithms difficult as within the same model with a given order one could find an example for which one of the methods performs favourably well or fails [6, 8]. Our aim is to improve the performance of the model order selection criteria in cases where the SNR is low by considering a model-selection searching procedure that takes into account not only the full-model order search but also a partial model order search within the given model order. Understandably, the improvement in the performance of the model order estimation is at the expense of additional computational complexity.

Comedy hints at the tragedy beneath [REVIEW]

THE Little Dog Laughed. By Douglas Carter Beane. Queensland Theatre Company. Cremorne Theatre, Brisbane. February 11. DOUGLAS Carter Beane's The Little Dog Laughed is a comedy about truth and its consequences. Set mainly in New York, the story follows film star Mitchell Green's developing relationship with Alex, a rentboy he calls one night while drunk and lonely in a hotel room. Scenes in which Mitchell and Alex test the strength of something they seem to have found together are punctuated by monologues from Mitchell's agent Diane and Alex's ex-girlfriend Ellen. We start to see glimpses of their separate lives, what their shared life might look like and, eventually, a crisis that brings all four characters together in the pursuit of a somewhat conflicted set of ideas about what happiness is and what it takes to be happy.

Engaging operations management students by designing the unit with industry focus

Operations management is an area concerned with the production of goods and services ensuring that business operations are efficient in utilizing resource and effective to meet customer requirements. It deals with the design and management of products, processes, services and supply chains and considers the acquisition, development, and effective and efficient utilization of resources. Unlike other engineering subjects, content of these units could be very wide and vast. It is therefore necessary to cover the content that is most related to the contemporary industries. It is also necessary to understand what engineering management skills are critical for engineers working in the contemporary organisations. Most of the operations management books contain traditional Operations Management techniques. For example ‘inventory management’ is an important topic in operations management. All OM books deal with effective method of inventory management. However, new trend in OM is Just in time (JIT) delivery or minimization of inventory. It is therefore important to decide whether to emphasise on keeping inventory (as suggested by most books) or minimization of inventory. Similarly, for OM decisions like forecasting, optimization and linear programming most organisations now a day’s use software. Now it is important for us to determine whether some of these software need to be introduced in tutorial/ lab classes. If so, what software? It is established in the Teaching and Learning literature that there must be a strong alignment between unit objectives, assessment and learning activities to engage students in learning. Literature also established that engaging students is vital for learning. However, engineering units (more specifically Operations management) is quite different from other majors. Only alignment between objectives, assessment and learning activities cannot guarantee student engagement. Unit content must be practical oriented and skills to be developed should be those demanded by the industry. Present active learning research, using a multi-method research approach, redesigned the operations management content based on latest developments in Engineering Management area and the necessity of Australian industries. The redesigned unit has significantly helped better student engagement and better learning. It was found that students are engaged in the learning if they find the contents are helpful in developing skills that are necessary in their practical life.

International students in Australian universities : gap between student expectations and realities

Australian Universities are very successful in attracting large number of international students. A large proportion of University revenue comes from the full fee paying international students. However, there have been many reports that international students face numerous problems when they arrive in Australia. The common management practice is to provide support staff services to deal with the orientation and welfare of international students. Such service units act as intermediaries between the students and the teaching and learning community of the university. However, the actual experience of international students may be difficult for support staff, counsellors, advisers and academic staff to anticipate. There is little information on the actual experience of students relative to their expectations. This study aimed at securing a deeper understanding of the contextually relevant issues facing by international students in Australian universities in order to develop management strategies aimed at improved teaching and learning outcomes for international students. Using a highly reliable survey questionnaire, a questionnaire survey was conducted among the international students at Queensland University of Technology (QUT), Brisbane, Australia. About 180 engineering students responded in the survey resulting in a response rate of 81%. Results indicate that international students face many difficulties including understanding colloquial language, Australian accent, cost of tuition, feelin isolation, safety, security, health services, accommodation and part time jobs. They also face difficulty in coping with learning methods in Australia, particularly in research report writing. However, they are happy with their lecturers and find them very helpful. Many of the students lacked the information regarding various community groups, recreational and sports facilities in Australia before arriving. Findings of the study show that there is a significant gap between the expectation of the students before coming to Australia and actual experience they experience here. Importantly, there is a lack of coordination between international students, international student services (ISS) and university management and as a consequence there have been little improvement in conditions. There is no direct link between student experience and University management. Many important suggestions arisen from this study and most important suggestion is that the student information system should be integrated with the University enterprise resource planning (ERP) to reduce the huge gap between international student expectation and actual experiences.

A simple orientation robust transmit polarization signalling scheme

A special transmit polarization signalling scheme is presented to alleviate the power reduction as a result of polarization mismatch from random antenna orientations. This is particularly useful for hand held mobile terminals typically equipped with only a single linearly polarized antenna, since the average signal power is desensitized against receiver orientations. Numerical simulations also show adequate robustness against incorrect channel estimations.

Towards improvement of autonomous glider navigation accuracy through the use of regional ocean models

Autonomous underwater gliders are robust and widely-used ocean sampling platforms that are characterized by their endurance, and are one of the best approaches to gather subsurface data at the appropriate spatial resolution to advance our knowledge of the ocean environment. Gliders generally do not employ sophisticated sensors for underwater localization, but instead dead-reckon between set waypoints. Thus, these vehicles are subject to large positional errors between prescribed and actual surfacing locations. Here, we investigate the implementation of a large-scale, regional ocean model into the trajectory design for autonomous gliders to improve their navigational accuracy. We compute the dead-reckoning error for our Slocum gliders, and compare this to the average positional error recorded from multiple deployments conducted over the past year. We then compare trajectory plans computed on-board the vehicle during recent deployments to our prediction-based trajectory plans for 140 surfacing occurrences.

Efficient control of an autonomous underwater vehicle while accounting for thruster failure

This paper is concerned with the design and implementation of control strategies onto a test-bed vehicle with six degrees-of-freedom. We design our trajectories to be efficient in time and in power consumption. Moreover, we also consider cases when actuator failure can arise and discuss alternate control strategies in this situation. Our calculations are supplemented by experimental results.

A first extension of geometric control theory to underwater vehicles

This paper serves as a first study on the implementation of control strategies developed using a kinematic reduction onto test bed autonomous underwater vehicles (AUVs). The equations of motion are presented in the framework of differential geometry, including external dissipative forces, as a forced affine connection control system. We show that the hydrodynamic drag forces can be included in the affine connection, resulting in an affine connection control system. The definitions of kinematic reduction and decoupling vector field are thus extended from the ideal fluid scenario. Control strategies are computed using this new extension and are reformulated for implementation onto a test-bed AUV. We compare these geometrically computed controls to time and energy optimal controls for the same trajectory which are computed using a previously developed algorithm. Through this comparison we are able to validate our theoretical results based on the experiments conducted using the time and energy efficient strategies.

Everyone wants Web 2.0

The interactive nature of Information and Communication Technologies (ICT) is the impetus for the adoption of digital technologies by students for socialising and communicating in new ways. In particular these new ways of communication have embraced web 2.0 technologies such as Facebook© ©, however, teaching practices within educational institutions have remained relatively unchanged. This paper explores the use of the web 2.0 technology Facebook© in a Higher Educational setting to support undergraduate students. It further highlights how students in a developing country currently use this technology and their expectations for the future use of this web 2.0 technology.

Asset health prediction using condition indicators and operating environment indicators : a case study

Prognostics and asset life prediction is one of research potentials in engineering asset health management. We previously developed the Explicit Hazard Model (EHM) to effectively and explicitly predict asset life using three types of information: population characteristics; condition indicators; and operating environment indicators. We have formerly studied the application of both the semi-parametric EHM and non-parametric EHM to the survival probability estimation in the reliability field. The survival time in these models is dependent not only upon the age of the asset monitored, but also upon the condition and operating environment information obtained. This paper is a further study of the semi-parametric and non-parametric EHMs to the hazard and residual life prediction of a set of resistance elements. The resistance elements were used as corrosion sensors for measuring the atmospheric corrosion rate in a laboratory experiment. In this paper, the estimated hazard of the resistance element using the semi-parametric EHM and the non-parametric EHM is compared to the traditional Weibull model and the Aalen Linear Regression Model (ALRM), respectively. Due to assuming a Weibull distribution in the baseline hazard of the semi-parametric EHM, the estimated hazard using this model is compared to the traditional Weibull model. The estimated hazard using the non-parametric EHM is compared to ALRM which is a well-known non-parametric covariate-based hazard model. At last, the predicted residual life of the resistance element using both EHMs is compared to the actual life data.

Digital image processing techniques for pavement macro-texture analysis

Road surface macro-texture is an indicator used to determine the skid resistance levels in pavements. Existing methods of quantifying macro-texture include the sand patch test and the laser profilometer. These methods utilise the 3D information of the pavement surface to extract the average texture depth. Recently, interest in image processing techniques as a quantifier of macro-texture has arisen, mainly using the Fast Fourier Transform (FFT). This paper reviews the FFT method, and then proposes two new methods, one using the autocorrelation function and the other using wavelets. The methods are tested on pictures obtained from a pavement surface extending more than 2km's. About 200 images were acquired from the surface at approx. 10m intervals from a height 80cm above ground. The results obtained from image analysis methods using the FFT, the autocorrelation function and wavelets are compared with sensor measured texture depth (SMTD) data obtained from the same paved surface. The results indicate that coefficients of determination (R2) exceeding 0.8 are obtained when up to 10% of outliers are removed.

Development of an online condition monitoring system for slow speed machinery

One of the main challenges of slow speed machinery condition monitoring is that the energy generated from an incipient defect is too weak to be detected by traditional vibration measurements due to its low impact energy. Acoustic emission (AE) measurement is an alternative for this as it has the ability to detect crack initiations or rubbing between moving surfaces. However, AE measurement requires high sampling frequency and consequently huge amount of data are obtained to be processed. It also requires expensive hardware to capture those data, storage and involves signal processing techniques to retrieve valuable information on the state of the machine. AE signal has been utilised for early detection of defects in bearings and gears. This paper presents an online condition monitoring (CM) system for slow speed machinery, which attempts to overcome those challenges. The system incorporates relevant signal processing techniques for slow speed CM which include noise removal techniques to enhance the signal-to-noise and peak-holding down sampling to reduce the burden of massive data handling. The analysis software works under Labview environment, which enables online remote control of data acquisition, real-time analysis, offline analysis and diagnostic trending. The system has been fully implemented on a site machine and contributing significantly to improve the maintenance efficiency and provide a safer and reliable operation.

An application of the CBBE model to assess brand loyalty for a long haul travel destination

In the past two decades there has been increasing interest in branding tourism destinations in an effort to meaningfully differentiate against a myriad of competing places that offer similar attractions and facilities. The academic literature relating to destination branding commenced only as recently as 1998, and there remains a dearth of empirical data that tests the effectiveness of brand campaigns, particularly in terms of enhancing destination loyalty. This paper reports the results of an investigation into destination brand loyalty for Australia as a long haul destination in a South American market. In spite of the high level of academic interest in the measurement of perceptions of destinations since the 1970s, few previous studies have examined perceptions held by South American consumers. Drawing on a model of consumer-based brand equity (CBBE), antecedents of destination brand loyalty was tested with data from a large Chilean sample of travelers, comprising a mix of previous visitors and non-visitors to Australia. Findings suggest that destination brand awareness, brand image, and brand value are positively related to brand loyalty for a long-haul destination. However, destination brand quality was not significantly related. The results also indicate that Australia is a more compelling destination brand for previous visitors compared to non-visitors.

The social media (r)evolution : Obama's political campaign

This paper addresses how social media was used to leverage votes in new media environments. Barack Obama’s social media campaign is analysed and illustrates how the Obama brand benefited from integrating social media into the campaign. Voting behaviour has changed; politicians are continually seeking new ways to communicate with their constituents. Voting on political ‘brands’ is based on an identity or image, rather than central issues. While political parties rely upon an integrated marketing communication (IMC) approach, with a focus on building the (political) brand of the party and brand relationships, communication is no longer fully controlled by the marketers.

Eigengaze : covert behavioral biometric exploiting visual attention characteristics

It is possible for the visual attention characteristics of a person to be exploited as a biometric for authentication or identification of individual viewers. The visual attention characteristics of a person can be easily monitored by tracking the gaze of a viewer during the presentation of a known or unknown visual scene. The positions and sequences of gaze locations during viewing may be determined by overt (conscious) or covert (sub-conscious) viewing behaviour. This paper presents a method to authenticate individuals using their covert viewing behaviour, thus yielding a unique behavioural biometric. A method to quantify the spatial and temporal patterns established by the viewer for their covert behaviour is proposed utilsing a principal component analysis technique called `eigenGaze'. Experimental results suggest that it is possible to capture the unique visual attention characteristics of a person to provide a simple behavioural biometric.