Deep Room Recognition Using Inaudible Echos

Recent years have seen the increasing need of location awareness by mobile applications. This paper presents a room-level indoor localization approach based on the measured room's echos in response to a two-millisecond single-tone inaudible chirp emitted by a smartphone's loudspeaker. Different from other acoustics-based room recognition systems that record full-spectrum audio for up to ten seconds, our approach records audio in a narrow inaudible band for 0.1 seconds only to preserve the user's privacy. However, the short-time and narrowband audio signal carries limited information about the room's characteristics, presenting challenges to accurate room recognition. This paper applies deep learning to effectively capture the subtle fingerprints in the rooms' acoustic responses. Our extensive experiments show that a two-layer convolutional neural network fed with the spectrogram of the inaudible echos achieve the best performance, compared with alternative designs using other raw data formats and deep models. Based on this result, we design a RoomRecognize cloud service and its mobile client library that enable the mobile application developers to readily implement the room recognition functionality without resorting to any existing infrastructures and add-on hardware. Extensive evaluation shows that RoomRecognize achieves 99.7%, 97.7%, 99%, and 89% accuracy in differentiating 22 and 50 residential/office rooms, 19 spots in a quiet museum, and 15 spots in a crowded museum, respectively. Compared with the state-of-the-art approaches based on support vector machine, RoomRecognize significantly improves the Pareto frontier of recognition accuracy versus robustness against interfering sounds (e.g., ambient music).Comment: 29 page

Thermodynamics of Spin-1/2 AF-AF-F and F-F-AF Trimerized Quantum Heisenberg Chains

The magnetization process, the susceptibility and the specific heat of the spin-1/2 AF-AF-F and F-F-AF trimerized quantum Heisenberg chains have been investigated by means of the transfer matrix renormalization group (TMRG) technique as well as the modified spin-wave (MSW) theory. A magnetization plateau at $m=1/6$ for both trimerized chains is observed at low temperature. The susceptibility and the specific heat show various behaviors for different ferromagnetic and antiferromagnetic interactions and in different magnetic fields. The TMRG results of susceptibility and the specific heat can be nicely fitted by a linear superposition of double two-level systems, where two fitting equations are proposed. Three branch excitations, one gapless excitation and two gapful excitations, for both systems are found within the MSW theory. It is observed that the MSW theory captures the main characteristics of the thermodynamic behaviors at low temperatures. The TMRG results are also compared with the possible experimental data.Comment: 11 pages, 10 figure

Decreased demand for olfactory periglomerular cells impacts on neural precursor cell viability in the rostral migratory stream

The subventricular zone (SVZ) provides a constant supply of new neurons to the granule cell-layer of the olfactory bulb (OB) and new interneurons for the glomerular layer likely arise from the rostral migratory stream (RMS). Different studies have investigated the role of olfactory sensory input to neural precursor cell (NPC) turnover in the SVZ but it was not addressed if a reduced demand specifically for periglomerular neurons impacts on NPC-traits in the RMS. We here report that membrane type-1 matrix metalloproteinase (MT1-MMP) deficient mice have reduced complexity of the nasal turbinates, decreased sensory innervation of the OB, reduced numbers of olfactory glomeruli and reduced OB-size without alterations in SVZ neurogenesis. The rostral migratory stream (RMS) was fully preserved in MT1-MMP-deficient mice, but we detected an increase in cell death-levels in the distal RMS, as compared to controls. BrdU-tracking experiments showed that homing of NPCs specifically to the glomerular layer was reduced in MT1-MMP-deficient mice in contrast to controls while numbers of tracked cells remained equal in other OB-layers throughout all experimental groups. Altogether, our data show the demand for olfactory interneurons in the glomerular layer modulates cell turnover in the RMS, but has no impact on subventricular neurogenesis

Bi-axially loaded slender reinforced concrete columns subjected to sustained loads

A generalized analytical approach is presented in this research to predict the behavior both of slender and short reinforced concrete columns under sustained biaxial eccentric load. The present analysis proposes equations established at a cross section of a reinforced concrete column by combining force equilibrium, constitutive law, and compatibility conditions. The strain and curvature of each section and the deflection of the column can then be obtained and resolved. The established creep computation models, recommended separately by American Concrete Institute (ACI) 209R-92 and the Comite\u27 Euro-International du Be\u27ton (CEB)-FIP 1990 Model Code have been used to calculate creep and shrinkage for a member under a constant elastic compressive concrete strain for a given period. This present analysis also proposes a computerized method for time and strain adjustment. The Time and Strain Adjustment of Creep Method, combining a creep calculation with a constant elastic strain such as those mentioned above, the creep strain at each cross section can then be calculated, stored and adjusted to age of concrete, load changes and deflection modifications during each time increment phase. In the conventional load-deflection analysis process, with projected transformations, a spatial deflection curve is resolved into a couple of planar curves located separately in two orthogonal plans. Based on the force equilibrium equations of inner force at a column section, a set of three simultaneous non-linear differential equations are derived to establish the relationships between the planar curve functions with the eccentric load upon the top of column. Using the Green\u27s Integral Formula, the strain and stress nonlinear functions and column section properties can be solely integrated into a few important coefficients of the differential equations. Thus, it makes the approach also suitable for columns with non-rectangular sections and any kinds of constitutive laws of materials. The presented rational computer analysis results have been compared with the existing bi-axial and uniaxial experimental data, which are available in literature. They indicate that the results from the proposed analysis correlate with experimental data well