A Nested Sensor Array Focusing on Near Field Targets

A nested virtual array subband beamforming system is proposed for applications where broadband signal targets are located within the near field of the array. Subband multirate processing and near field beamforming techniques are used jointly for the nested array to improve the performances and reduce the computational complexity. A new noise model, namely the broadband near field spherically isotropic noise model, is also proposed for the optimization design of near field beamformers. It is shown that near field beamforming is essential for better distance discrimination of near field targets, reduced beampattern variations for broadband signals, and stronger reverberation suppression

Robust Near-Field Adaptive Beamforming with Distance Discrimination

This paper proposes a robust near-field adaptive beamformer for microphone array applications in small rooms. Robustness against location errors is crucial for near-field adaptive beamforming due to the difficulty in estimating near-field signal locations especially the radial distances. A near-field regionally constrained adaptive beamformer is proposed to design a set of linear constraints by filtering on a low rank subspace of the near-field signal over a spatial region and frequency band such that the beamformer response over the designed spatial-temporal region can be accurately controlled by a small number of linear constraint vectors. The proposed constraint design method is a systematic approach which guarantees real arithmetic implementation and direct time domain algorithms for broadband beamforming. It improves the robustness against large errors in distance and directions of arrival, and achieves good distance discrimination simultaneously. We show with a nine-element uniform linear array that the proposed near-field adaptive beamformer is robust against distance errors as large as ±32% of the presumed radial distance and angle errors up to ±20⁰. It can suppress a far field interfering signal with the same angle of incidence as a near-field target by more than 20 dB with no loss of the array gain at the near-field target. The significant distance discrimination of the proposed near-field beamformer also helps to improve the dereverberation gain and reduce the desired signal cancellation in reverberant environments

A Microphone Array System for Multimedia Applications with Near-Field Signal Targets

A microphone array beamforming system is proposed for multimedia communication applications using four sets of small planar arrays mounted on a computer monitor. A new virtual array approach is employed such that the original signals received by the array elements are weighted and delayed to synthesize a large, nonuniformly spaced, harmonically nested virtual array covering the frequency band [50, 7000] Hz of the wideband telephony. Subband multirate processing and near-field beamforming techniques are then used jointly by the nested virtual array to improve the performances in reverberant environments. A new beamforming algorithm is also proposed using a broadband near-field spherically isotropic noise model for array optimization. The near-field noise model assumes a large number of broadband random noises uniformly distributed over a sphere with a finite radius in contrast to the conventional far-field isotropic noise model which has an infinite radius. The radius of the noise model, thus, adds a design parameter in addition to its power for tradeoffs between performance and robustness. It is shown that the near-field beamformers designed by the new algorithm can achieve more than 8-dB reverberation suppression while maintaining sufficient robustness against background noises and signal location errors. Computer simulations and real room experiments also show that the proposed array beamforming system reduces beampattern variations for broadband signals, obtains strong noise and reverberation suppression, and improves the sound quality for near-field targets

Image registration of ex-vivo MRI to sparsely sectioned histology of hippocampal and neocortical temporal lobe specimens.

Intractable or drug-resistant epilepsy occurs in up to 30% of epilepsy patients, with many of these patients undergoing surgical excision of the affected brain region to achieve seizure control. Recent magnetic resonance imaging (MRI) sequences and analysis techniques have the potential to detect abnormalities not identified with diagnostic MRI protocols. Prospective studies involving pre-operative imaging and collection of surgically-resected tissue provide a unique opportunity for verification and tuning of these image analysis techniques, since direct comparison can be made against histopathology, and can lead to better prediction of surgical outcomes and potentially less invasive procedures. To carry out MRI and histology comparison, spatial correspondence between the MR images and the histology images must be found. Towards this goal, a novel pipeline is presented here for bringing ex-vivo MRI of surgically-resected temporal lobe specimens and digital histology into spatial correspondence. The sparsely-sectioned histology images represent a challenge for 3D reconstruction which we address with a combined 3D and 2D registration algorithm that alternates between slice-based and volume-based registration with the ex-vivo MRI. We evaluated our registration method on specimens resected from patients undergoing anterior temporal lobectomy (N=7) and found our method to have a mean target registration error of 0.76±0.66 and 0.98±0.60 mm for hippocampal and neocortical specimens respectively. This work allows for the spatially-local comparison of histology with post-operative MRI and paves the way for eventual correlation with pre-operative MRI image analysis techniques

Eco-Nudging: Interactive Digital Design to Solicit Immediate Energy Actions in The Built Space

In the built space, building occupants, their behaviours and control actions are research areas that have gained a lot of attention. This is well justified since energy behaviours can result in differences of up to 25% in building energy consumption. Previous research recommends exploring ways to influence occupants' energy behaviour – through eco-feedback and by directly engaging occupants with building controls. Very little attention has been given to the role digital art and design can play in soliciting and changing human energy-related actions and behaviours in the built space. This paper proposes a new process that combines eco-feedback, gamification, and ecological digital art to trigger occupants to take immediate and precise control actions in the built space. We design, deploy and test this by creating an immersive human-building-interaction apparatus, which we place in a month-long exhibition. This experimental interface was informed by a novel vision for engagement-based human-building interactions deeply rooted in aesthetics, digital art and design. It also uses digital art to mediate between the occupants and energy-performance of spaces by redefining their relationship with and perception of energy – moving from metrics and quantities understanding to one that is art and emotion-based. The analysis reveals that this new type of human-engagement-based interactive building-control mechanism can add a significant layer of influence on energy-related actions – without revoking the individuals' ability to control their environment. It also highlights digital design and art's power in guiding actions and interactions with the built space

Eyes on the Goal! Exploring Interactive Artistic Real-Time Energy Interfaces for Target-Specific Actions in the Built Environment

Current research is focused on sensing and modeling occupant behavior to predict it and automate building controls. Another line of research recommends influencing the behavior of occupants through feedback mechanisms and engagement. Yet, most of the work has focused on pushing occupants to reduce energy consumption over a long time and does not explore the potential to guide users to take specific actions promptly. The study examines a new interface mechanism that aims to solicit immediate and predefined actions from occupants. Building on seminal research in the field, the study uses art visualization to reinterpret social feedback. We test this approach in an immersive interaction space where participants react to artistic visuals to attain predefined settings for three indoor devices. In the 197 interactions recorded, participants’ overall actions conformed with the predefined goals. The participants were able to reach all or some of the targets in more than 80%, within an average of less than 30 seconds. We also see that complementing the visuals with textual hints improved the interaction in terms of engagement and accuracy. We conclude that ambient, abstract, and artistic real-time goal-driven feedback is effective in influencing immediate actions. We recommend that guiding occupants didactically has a strong potential for advancing building controls

We gain a lot… but what are we losing?: A critical exploration of the implications of digital design technologies on sustainable architecture

In the field of architecture, new technologies are enabling us to promptly simulate, quantify, and compare multitudes of design alternatives and consider an ever more expanding list of environmental and economic parameters within the early design phases of projects. However, architecture today veers further towards non-neutral technologies, changing our culture, introducing new values, and (re)shaping our social ideals. The change of media, from the manual to the digital, has deeply transformed architecture and city design. There is undoubtedly progress, but what are we losing in this automation, virtualization and over-digitalization? Are architects—creators of space, human experience, and cultural capital—starting to occupy the role of technicians? Sustainable architecture is a field that is already experiencing tensions between the quantitative and the qualitative, the optimum and the ethical, and the parametric and haptic methods. Yet the rapidly evolving CAAD technologies overlook many of the non-quantifiable values of these binaries. Gains in speed and efficiency in the design process with the help of parametric design may be challenging the designer’s reflection-in-action process required for critical architecture while ethical, cultural, and human dimensions can hardly be modelled algorithmically. Similarly, computational thinking and digitalization in architectural education, have yet to come to terms ‫‪with‬‬ ‫‪the‬‬ ‫‪loss‬‬ ‫‪of‬‬ ‫‪analogue‬‬ ‫‪ways‬‬ ‫‪of‬‬ ‫‪learning‬‬ ‫‪that‬‬ ‫‪favour‬‬ ‫‪a‬‬ ‫‪more‬‬ ‫‪diverse‬‬ ‫‪and‬‬ ‫‪inclusive‬‬ ‫‪classroom‬‬ ‫‪environment.‬‬ ‫‪Instead‬‬ ‫‪of‬‬ ‫‪keeping‬‬ ‫‪the‬‬ ‫‪analogue‬‬ ‫‪and‬‬ ‫‪the‬‬ ‫‪haptic‬‬ ‫‪practices‬‬ ‫‪away‬‬ ‫‪from‬‬ ‫‪the‬‬ ‫‪immaculate‬‬ ‫‪realm‬‬ ‫‪of‬‬ ‫‪CAAD,‬‬ ‫‪this‬‬ ‫‪paper‬‬ ‫‪argues‬‬ ‫‪for‬‬ ‫‪hybrid‬‬ ‫‪technologies‬‬ ‫‪that‬‬ ‫‪recognize‬‬ ‫‪these‬‬ ‫‪practices‬‬ ‫‪and‬‬ ‫‪their‬‬ ‫‪value‬‬ ‫‪in‬‬ ‫‪sustainable‬‬ ‫‪design‬‬ ‫‪and‬‬ ‫‪incorporate‬‬ ‫‪them.‬‬ ‫‪Film‬‬ ‫‪animation,‬‬ ‫‪as‬‬ ‫‪a‬‬ ‫‪branch‬‬ ‫‪of‬‬ ‫‪architecture’s‬‬ ‫‪most‬‬ ‫‪expressive‬‬ ‫‪means,‬‬ ‫‪film,‬‬ ‫‪can‬‬ ‫‪serve‬‬ ‫‪as‬‬ ‫‪a‬‬ ‫‪paradigm‬‬ ‫‪of‬‬ ‫‪a‬‬ ‫‪feasible‬‬ ‫‪disruptive‬‬ ‫‪technology,‬‬ ‫‪but‬‬ ‫‪most‬‬ ‫‪importantly,‬‬ ‫‪as‬‬ ‫‪an‬‬ ‫‪indicator‬‬ ‫‪of‬‬ ‫‪the‬‬ ‫‪hybridity‬‬ ‫‪between‬‬ ‫‪the‬‬ ‫‪handmade‬‬ ‫‪and‬‬ ‫‪the‬‬ ‫‪digital‬‬ ‫‪and‬‬ ‫‪its‬‬ ‫‪effectiveness‬‬ ‫‪in‬‬ ‫‪expressing‬‬ ‫‪vital‬‬ ‫‪elements‬‬ ‫‪of‬‬ ‫‪sustainability‬‬ ‫‪that‬‬ ‫‪are‬‬ ‫‪otherwise‬‬ ‫‪dismissed.‬

Quantitative relaxometry and diffusion MRI for lateralization in MTS and non-MTS temporal lobe epilepsy.

We developed novel methodology for investigating the use of quantitative relaxometry (T1 and T2) and diffusion tensor imaging (DTI) for lateralization in temporal lobe epilepsy. Patients with mesial temporal sclerosis confirmed by pathology (N=8) and non-MTS unilateral temporal lobe epilepsy (N=6) were compared against healthy controls (N=19) using voxel-based analysis restricted to the anterior temporal lobes, and laterality indices for each MRI metric (T1, T2, fractional anisotropy (FA), mean diffusivity, axial and radial diffusivities) were computed based on the proportion of significant voxels on each side. The diffusivity metrics were the most lateralizing MRI metrics in MTS and non-MTS subsets, with significant differences also seen with FA, T1 and T2. Patient-specific multi-modal laterality indices were also computed and were shown to clearly separate the left-onset and right-onset patients. Marked differences between left-onset and right-onset patients were also observed, with left-onset patients exhibiting stronger laterality indices. Finally, neocortical abnormalities were found to be more common in the non-MTS patients. These preliminary results on a small sample size support the further investigation of quantitative MRI and multi-modal image analysis in clinical determination of seizure onset. The presence of more neocortical abnormalities in the non-MTS group suggests a role in seizure onset or propagation and motivates the investigation of more sensitive histopathological analysis to detect and delineate potentially subtle neocortical pathology

Registration of in-vivo to ex-vivo MRI of surgically resected specimens: A pipeline for histology to in-vivo registration.

BACKGROUND: Advances in MRI have the potential to improve surgical treatment of epilepsy through improved identification and delineation of lesions. However, validation is currently needed to investigate histopathological correlates of these new imaging techniques. The purpose of this work is to develop and evaluate a protocol for deformable image registration of in-vivo to ex-vivo resected brain specimen MRI. This protocol, in conjunction with our previous work on ex-vivo to histology registration, completes a registration pipeline for histology to in-vivo MRI, enabling voxel-based validation of novel and existing MRI techniques with histopathology. NEW METHOD: A combination of image-based and landmark-based 3D registration was used to register in-vivo MRI and the ex-vivo MRI from patients (N=10) undergoing epilepsy surgery. Target registration error (TRE) was used to assess accuracy and the added benefit of deformable registration. RESULTS: A mean TRE of 1.35±0.11 and 1.41±0.33mm was found for neocortical and hippocampal specimens respectively. Statistical analysis confirmed that the deformable registration significantly improved the registration accuracy for both specimens. COMPARISON WITH EXISTING METHODS: Image registration of surgically resected brain specimens is a unique application which presents numerous technical challenges and that have not been fully addressed in previous literature. Our computed TRE are comparable to previous attempts tackling similar applications, as registering in-vivo MRI to whole brain or serial histology. CONCLUSION: The presented registration pipeline finds dense and accurate spatial correspondence between in-vivo MRI and histology and allows for the spatially local and quantitative assessment of pathological correlates in MRI