Direct Position Determination of Noncircular Sources with Multiple Nested Arrays: Reduced Dimension Subspace Data Fusion

Direct position determination (DPD) of noncircular (NC) sources with multiple nested arrays (NA) is investigated in this paper. Noncircular sources are used to expand the dimension of the received signal matrix, so the number of identifiable information sources and the accuracy of direct position determination are improved. Furthermore, nested array increases spatial degree of freedom. In this paper, the high-dimensional search problem of noncircular sources is investigated. Therefore, we propose algorithm dimension reduction subspace data fusion (RD-SDF) to reduce complexity and increase positioning accuracy. Simulation results show that the proposed RD-SDF algorithm for multiple nested arrays with noncircular sources has improved positioning accuracy with higher spatial degree of freedom than SDF, Capon, and two-step algorithms with uniform linear array and circular sources (CS).

Experimental demonstration of multiple dimensional coding decoding for image transfer with controllable vortex arrays

Vortex beams carrying orbital angular momentum (OAM), which featuring helical phase front, have been regarded as an alternative spatial degree of freedom for optical mode coding and multiplexing. For most reported OAM-based mode coding schemes, data information is only encoded by different OAM mode states. In this paper, we introduce a novel design technique to construct vortex array phase grating (VAPGs) for the flexible generation of vortex arrays, and employ the proposed VAPGs to realize multi-dimensional space/mode/amplitude coding/decoding. By designing VAPGs with different parameters and loading them on to a single spatial light modulator (SLM), we successfully generate vortex array with different mode states and relative power in the experiments. Moreover, a 10-bit multi-dimensional space/mode/amplitude data coding/decoding scheme for image transfer in free-space link with a zero bit-error-rate is experimentally demonstrated, which confirm the feasibility of our proposed VAPG-based coding/decoding scheme.

Experimental Demonstration of Multi-dimensional Coding/decoding for Image Transfer with Controllable Vortex Arrays

Vortex beams carrying orbital angular momentum (OAM), which featuring helical phase front, have been regarded as an alternative spatial degree of freedom for optical mode coding and multiplexing. For most reported OAM-based mode coding schemes, data information is only encoded by different OAM mode states. In this paper, we introduce a novel design technique to construct vortex array phase grating (VAPGs) for the flexible generation of vortex arrays, and employ the proposed VAPGs to realize multi-dimensional space/mode/amplitude coding/decoding. By designing VAPGs with different parameters and loading them on to a single spatial light modulator (SLM), we successfully generate vortex array with different mode states and relative power in the experiments. Moreover, a 10-bit multi-dimensional space/mode/amplitude data coding/decoding scheme for image transfer in free-space link with a zero bit-error-rate is experimentally demonstrated, which confirm the feasibility of our proposed VAPG-based coding/decoding scheme.

Neighbourhood deprivation and obesity among 5656 pre-school children—findings from mandatory school enrollment examinations

The risk of child obesity is strongly related to socioeconomic factors such as individual socioeconomic position (SEP) and neighbourhood deprivation. The present study analyses whether the relationship between neighbourhood deprivation and child obesity differs by child’s individual SEP. Data from 5656 children (5–7 years) from the mandatory school enrollment examinations of the pre-school cohorts 2017/2018 in Düsseldorf were analysed. Obesity was determined by the age- and gender-specific body mass index (BMI); neighbourhood deprivation by using the socio-spatial degree of deprivation of the children’s residential addresses; and individual SEP by the level of parental education. Using Poisson regression, we estimated prevalence ratios (PR with 95% confidence interval (CI)) of child obesity by neighbourhood deprivation and parental education. Interactions between neighbourhood deprivation and parental education were tested. The prevalence of child obesity increases with the degree of neighbourhood deprivation. Compared to children living in low deprivation neighbourhoods, the proportion of obese children was twice as high in high deprivation neighbourhoods (PR=2.02; CI=1.46–2.78). Likewise, children from families with medium and low education have twice the risk for obesity compared to children with high parental education (PR=2.05; CI=1.46–2.78). The relationship between neighbourhood deprivation and child obesity was significantly moderated by parental education; it was stronger for higher parental education than for medium and low parental education (p<.001).Conclusion: Our findings suggest that children from deprived neighbourhoods and families with lower education have a higher risk for child obesity. The identification of particularly deprived neighbourhoods with structural interventions in combination with the strengthening of parental health literacy seems reasonable. What is Known:• Studies show that children from disadvantaged neighbourhoods are more frequently obese. What is New:• The relationship between neighbourhood deprivation and child obesity is significantly moderated by parental education. It is stronger for children with higher parental education than for children with medium and low parental education.

The Spatial Distribution of the Basic Education Schools in Lattakia City (Syria)

The main aim of the study is to detect the spatial degree of inequality and adequacies in the provision of first and second stage of basic education schools between different wards of Lattakia city, with respect to the population they serve. Secondary data were used for this study sourced from the inventory of the Educational Direction and the Direction of Statistic of Lattakia. Statistical techniques were employed to analyze data such as Mean deviation, Locational Quotient, Lorenz Curve and Ratio Schools/pop. The findings of the study indicated that the population and number of schools are not equidistributed. This revealed the existing of gaps in access to this facility between wards with some wards experiencing glut and concentration while other suffering lack and have no adequate access to this facility: for both F.S. and S.S. schools, L.Q. value varies from 0 to 2.6, and from 1.94 to 0.6 for S.S; Ratio population/schools varies from 1:2971.7 to 1:16776, and from 1:50329 to 1:5057. Lorenz Curve indicate that about 50 % of schools are enjoined by about 50 % for F.S. schools and 60% for S.S. schools. The study concluded that there was a need for intervention of planners and government in the provision of basic schools in deficient wards to enhance human development.

On Novel Access and Scheduling Schemes for IoT Communications

The Internet of Things (IoT) is expected to foster the development of 5G wireless networks and requires the efficient support for a large number of simultaneous short message communications. To address these challenges, some existing works utilize new waveform and multiuser superposition transmission schemes to improve the capacity of IoT communication. In this paper, we will investigate the spatial degree of freedom of IoT devices based on their distribution, then extend the multiuser shared access (MUSA) which is one of the typical MUST schemes to spatial domain, and propose two novel schemes, that is, the preconfigured access scheme and the joint spatial and code domain scheduling scheme, to enhance IoT communication. The results indicate that the proposed schemes can reduce the collision rate dramatically during the IoT random access procedure and improve the performance of IoT communication obviously. Based on the simulation results, it is also shown that the proposed scheduling scheme can achieve the similar performance to the corresponding brute-force scheduling but with lower complexity.

SOLUTION FOR THE PHOTOACOUSTIC WAVE EQUATION WITH A SINGLE SPATIAL DEGREE OF FREEDOM, BEER'S LAW ABSORPTION OF RADIATION AND MECHANICAL BARRIERS

A photoacoustic model with one degree of freedom in the spatial coordinates for a plane sample is studied. The model proposed considers a sample with Beer's law absorption immersed in a fluid with different acoustical impedance. An analytical solution for this problem is given. It is shown that the generated PA wave is composed of a pressure peak followed by a reflected and inverted pulse with diminished magnitude. It is also remarked that the form described for the pulse has a periodicity related to the sample's width and attenuated by the reflection coefficient. It is noted that, due to this attenuation, information about the sample's width is more easily detected at the irradiation side. Border cases are taken for equal impedances and infinite sample width.