Training Snapshots Research Articles

Robust Adaptive Beamforming Based on Interference Covariance Matrix Reconstruction and Steering Vector Estimation

Adaptive beamformers are sensitive to model mismatch, especially when the desired signal is present in training snapshots or when the training is done using data samples. In contrast to previous works, this correspondence attempts to reconstruct the interference-plus-noise covariance matrix instead of searching for the optimal diagonal loading factor for the sample covariance matrix. The estimator is based on the Capon spectral estimator integrated over a region separated from the desired signal direction. This is shown to be more robust than using the sample covariance matrix. Subsequently, the mismatch in the steering vector of the desired signal is estimated by maximizing the beamformer output power under a constraint that prevents the corrected steering vector from getting close to the interference steering vectors. The proposed adaptive beamforming algorithm does not impose a norm constraint. Therefore, it can be used even in applications where gain perturbations affect the steering vector. Simulation results demonstrate that the performance of the proposed adaptive beamformer is almost always close to the optimal value across a wide range of signal to noise and signal to interference ratios.

Are we there yet? Stagnation in entrepreneurship teaching practice 10 years on

Introduction If the popular press is to be believed, New Zealanders possess strong orientation (Riley, 1995). New Zealanders are told and encouraged to buy into the paradigm. For example, the book by John Hopkins, Blokes and Sheds (1998), later made into television series, celebrates the popular notion of the innovative nature that resides in the average New Zealander. There is also research evidence for this idea. On at least two occasions the Global Entrepreneurship Monitor, an international survey of activity within the participating country, has placed New Zealand highly in total activity (Reynolds, Camp, Bygrave, Autio, & Hay, 2001, 2004). A precise definition is problematic, though, with entrepreneurship commonly seen as involving business start-up by an individual. In contrast, Shane and Venkataraman (2000, p. 218) describe entrepreneurship as a process of opportunity discovery, evaluation and exploitation. This takes entrepreneurship out of the business relationship and makes it more way of thinking rather than way of starting business. This definition has much in common with the accepted idea of the orientation, which Lumpkin and Dess (1996) describe as having elements of innovation, creativity, and proactivity. Presumably this is the meaning intended in New Zealand Curriculum (NZC), which has as one of its vision statements that students will be enterprising and entrepreneurial (Ministry of Education, 2007, p. 8). Basic schooling is important as an avenue for cementing popular ideals. This research project looks at how preservice secondary school teacher trainees view the construct of entrepreneurship and finds that they appear to be uncertain about how to apply the concept. Our research was inspired by an earlier study in this area. In 1997 the New Zealand educational practitioner's journal set: Research Information for Teachers published paper entitled Inadequate perceptions of the educator's role (Cardow, 1997). paper reported on research conducted with preservice economics teachers and their instructors within New Zealand Colleges of Education. three conclusions reached were as follows: * Colleges of Education saw their goal as turning students into teachers, with the implication that the skills of creativity and innovation in business are what [teacher training] Colleges are set up to do (p. 4). * Instructors of preservice teachers envisaged those involved in entrepreneurship as being someone with The ability to make profit while being innovative and taking risk (p. 3), narrow perception which has not materially changed in the intervening period. * Preservice teachers and their instructors interpreted entrepreneurship as stepping outside normal bounds of making things happen (p. 3). Our research adds to the previous study by providing, in essence, snapshot of preservice teacher training from 1997 to 2008. We report on the changes to the New Zealand curriculum aimed at including entrepreneurship. research also uncovers the perceptions preservice teachers have regarding the implementation of entrepreneurship in their classrooms. We conclude that, despite the positive intentions of the Ministry of Education, 10 years on nothing much has changed. Background In 1987 the New Zealand public service, including the education sector, was subject to wide neoliberal reforms. In the postprimary sector these reforms were collectively known as Tomorrow's Schools. Essentially, governance issues were devolved to individual school boards of trustees. objective was to provide autonomy through independent management of secondary schools. philosophy of the government of the day was to encourage entrepreneurship within high school management. research outlined below critiques the situation 10 years after those reforms and during the tenure of another neoliberal Labour Government. …

Chapter 5 Issues of Name Authority Control in the Cataloging of Theses and Dissertations

SUMMARY Cataloging practice in providing personal names and corporate names as access points for print theses and dissertations (TDs) and for electronic theses and dissertations (ETDs) varies greatly. Likewise, authority control practice of these access points differs from institution to institution. Results of two relatively recent Autocat surveys revealed a wide range of practice in regard to authority control of these two types of access points for TD/ETDs. One of these surveys (conducted by the authors) also queried concerning membership in NACO (Name Authority Cooperative Program). The current study reviews the types of names (author, author's academic department, faculty advisor, committee members) that might be selected as access points in the TD/ETD catalog record and whether they should be under authority control. The authors provide a snapshot of NACO training and briefly describe the creation of Name Authority Records (NARs) for names of academic departments and for the student authors of TD/ETDs at Mississippi State University (MSU). The theses and dissertations program representative within the MSU library assisted in the implementation of a system for obtaining additional student information (preferred form of name and date of birth). Posted on a departmental drive, this information aids catalogers in creating unique personal name authority records. Implementation of authority control concepts such as those presented herein could improve access to TDs and ETDs.

Australian clinical psychology training program directors survey

A survey of clinical psychology program directors was conducted to provide an illustrative snapshot of clinical training in Australia. Postgraduate clinical psychology program directors from 27 universities in all States in Australia and the Australian Capital Territory offering postgraduate clinical training programs were emailed the survey; 19 surveys were returned. The present paper reports on a range of issues of relevance to clinical training programs, including numbers of students, types and content of courses, staff workload, relationship with professional bodies, practical training and university-based clinics, and concerns raised by directors. The information is intended to assist those responsible for training in clinical psychology in Australia in their work of increasing the quality of postgraduate training by being informed of the practices of other programs.

Logbooks: A Review of ENT registrar surgery

An annual snapshot of ENT SpR training is available at the Record of In-Training Assessment (RITA) when the regional trainees present their operative logs for scrutiny. Simple arithmetic reveals information about the quantity of operative training experience but rather less about quality. The logbook provides some insight into a trainee's surgical exposure and what opportunities are available in the region. This paper presents the summated logbooks of the ENT SpRs in the Eastern deanery presented at the annual RITA.

Robust localization using an omnidirectional appearance-based subspace model of environment

Appearance-based visual learning and recognition techniques that are based on models derived from a training set of 2D images are being widely used in computer vision applications. In robotics, they have received most attention in visual servoing and navigation. In this paper we discuss a framework for visual self-localization of mobile robots using a parametric model built from panoramic snapshots of the environment. In particular, we propose solutions to the problems related to robustness against occlusions and invariance to the rotation of the sensor. Our principal contribution is an “ eigenspace of spinning-images”, i.e., a model of the environment which successfully exploits some of the specific properties of panoramic images in order to efficiently calculate the optimal subspace in terms of principal components analysis (PCA) of a set of training snapshots without actually decomposing the covariance matrix. By integrating a robust recover-and-select algorithm for the computation of image parameters we achieve reliable localization even in the case when the input images are partly occluded or noisy. In this way, the robot is capable of localizing itself in realistic environments.

Adaptive sonar detection performance prediction in an uncertain ocean

This paper addresses the problem of predicting detection performance when the signal wavefront is uncertain and the noise field directionality is unknown. Passive sonar detection in this scenario typically involves robust adaptive beamforming with limited training data. The classical sonar equation, however, assumes the noise field and signal wavefront are known exactly. In this paper, we use the statistics of the generalized likelihood ratio test (GLRT) for the composite hypothesis of a multirank signal in Gaussian noise with unknown covariance matrix to evaluate the detection threshold (DT) as function of ocean uncertainty and number of noise training snapshots. Further, the trade-off between array gain (AG) and detection threshold (DT) is studied as a function of training sample size in a dynamic interference environment. Detection performance of the GLRT is characterized in terms of bounds on the middle 80th percentile of classical passive sonar figure of merit (FOM) and range-of-the-day (RD) over an ensemble of ocean environments. Different classes of environments including downward refracting and upward refracting scenarios are examined with particular attention to the Florida Straits region. Example performance prediction bounds are presented using real horizontal noise field and environmental data. [Work supported by ONR.]

Robust adaptive beamforming using worst-case performance optimization: a solution to the signal mismatch problem

Adaptive beamforming methods are known to degrade if some of underlying assumptions on the environment, sources, or sensor array become violated. In particular, if the desired signal is present in training snapshots, the adaptive array performance may be quite sensitive even to slight mismatches between the presumed and actual signal steering vectors (spatial signatures). Such mismatches can occur as a result of environmental nonstationarities, look direction errors, imperfect array calibration, distorted antenna shape, as well as distortions caused by medium inhomogeneities, near-far mismatch, source spreading, and local scattering. The similar type of performance degradation can occur when the signal steering vector is known exactly but the training sample size is small. In this paper, we develop a new approach to robust adaptive beamforming in the presence of an arbitrary unknown signal steering vector mismatch. Our approach is based on the optimization of worst-case performance. It turns out that the natural formulation of this adaptive beamforming problem involves minimization of a quadratic function subject to infinitely many nonconvex quadratic constraints. We show that this (originally intractable) problem can be reformulated in a convex form as the so-called second-order cone (SOC) program and solved efficiently (in polynomial time) using the well-established interior point method. It is also shown that the proposed technique can be interpreted in terms of diagonal loading where the optimal value of the diagonal loading factor is computed based on the known level of uncertainty of the signal steering vector. Computer simulations with several frequently encountered types of signal steering vector mismatches show better performance of our robust beamformer as compared with existing adaptive beamforming algorithms.

Computer-Generated Infrared Imagery for Combat-Vehicle Identification Training

Development of a computer-based system for generating simulated infrared (IR) imagery is described. The system provides realistic representations of IR targets and backgrounds for training soldiers in combat vehicle identification (CVI). Simulations of several fielded IR sensors enables system users to generate training imagery sets, both snapshots and animated sequences, showing realistic sensor effects. The system is workstation-based and has a user interface that permits a non-expert to generate desired imagery sets from menus of available models and scenarios.